1 Application form for EPA works approval How do I complete and submit this application form? Contacting EPA Please contact EPA: if you have any questions regarding the works approval process before preparing your application to confirm you require a works approval. About this application form This application form works in parallel with the works approval guidelines, which describe the level of information required to fill out the form appropriately. The sections of this form correspond directly to the sections of the guidelines. If, while preparing your application, you require advice on: the level of information needed further consultation with other agencies and neighbouring communities please schedule a meeting with EPA. This is usually best done once you have completed sections 1 to 8. The form allows you to add text directly to the form and save it. The completed form can then be printed and sent to EPA. The full application will usually be 10-20 pages, plus any required attachments (i.e. certificate of registration, site map, technical data etc.). If any of the information you are providing is `commercial in confidence' it should be marked as such, and attached separately. EPA welcomes feedback on the application form. How do I submit the application form? Once you have completed your works approval application, the following should be forwarded to Environment Protection Authority (GPO Box 4395, Melbourne 3001): completed application (sections 1 to 8 and the relevant A to I sections) application fee relevant supplementary information. Note: Please supply both a hard and electronic copy (CD is preferable). Once EPA confirms that your application is complete, the formal environmental assessment of your project begins.
Transcript
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Application form for EPA works approval
How do I complete and submit this application form?
Contacting EPA
Please contact EPA:
if you have any questions regarding the works approval process
before preparing your application to confirm you require a works approval.
About this application form
This application form works in parallel with the works approval guidelines, which describe the level of information required to fill out the form appropriately. The sections of this form correspond directly to the sections of the guidelines.
If, while preparing your application, you require advice on:
the level of information needed
further consultation with other agencies and neighbouring communities
please schedule a meeting with EPA. This is usually best done once you have completed sections 1 to 8.
The form allows you to add text directly to the form and save it. The completed form can then be printed and sent to EPA. The full application will usually be 10-20 pages, plus any required attachments (i.e. certificate of registration, site map, technical data etc.). If any of the information you are providing is `commercial in confidence' it should be marked as such, and attached separately.
EPA welcomes feedback on the application form.
How do I submit the application form?
Once you have completed your works approval application, the following should be forwarded to Environment Protection Authority (GPO Box 4395, Melbourne 3001):
completed application (sections 1 to 8 and the relevant A to I sections)
application fee
relevant supplementary information.
Note: Please supply both a hard and electronic copy (CD is preferable).
Once EPA confirms that your application is complete, the formal environmental assessment of your project begins.
261 Pyramid Rock Road Ventnor Bass Cost Shire Council
2. PROPOSAL
2.1 Project description
Westernport Water (WPW) is planning to upgrade the Cowes Wastewater Treatment Plant (CWWTP)
to serve projected increases in future population in the Phillip Island region and to treat the associated
increases in flows and loads.
The proposed CWWTP upgrade will primarily modify the existing plant facilities and operations to:
optimize plant treatment capacity and the ability to treat peak wet weather flows;
improve process performance and reliability; and
improve the quality of treated wastewater discharged to Bass Strait via the Pyramid Rock Road
outfall.
Minor works will also be undertaken to increase process capacity of the liquid and solid handling
facilities to meet the anticipated increase in loads.
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The primary objectives of this Works Approval Application to upgrade the CWWTP are:
Increase the average daily flow capacity of the plant up to 4.0 ML/d to handle predicted
increases flows and loads up to year 2021 (ie 25 per cent increase from current 2012 average
flow treated of 3.2 ML/d).
Optimise capacity of the biological secondary treatment process to handle peak flows up to
8.0 ML/d, and to provide up to 4 ML storage for flow attenuation during peak flow events. This
will provide secondary treatment of up to 3.0 times year 2021 average flow conditions.
Provide up to 12 ML storage for peak wet weather plant bypass flows in the effluent storage
lagoon and subsequent treatment if required. This will provide treatment of up to 24 ML/d (ie
up to 6 x average flow).
Increase nutrient removal in the plant by improving biological denitrification and process
stability to reduce the average total nitrogen concentration in the effluent to 25 mg/L (ie 17 per
cent decrease from the existing average value of 30 mg/L). Overall, the average total nitrogen
load discharged to Bass Strait will accordingly decrease up to year 2021.
Improve solids processing by increasing sludge stabilisation and dewatered solids
concentration prior to solar drying, with associated less energy consumption and odour
emissions.
Increase the average discharge flow limit to Bass Strait to 4.0 ML/d.
Include provision of a 100 m mixing zone in EPA licence CL76986.
The works will involve:
Bypass for screened and degritted flows greater than 12 ML/d direct to the 16 ML capacity
effluent storage lagoon during peak wet weather flow events (ie > 3.0 times average daily 2021
flow, and approximately a 1 in 4 year event). The bypass will protect the biological secondary
treatment process from solids washout. The bypassed screened and degritted volume of up to
12 ML will be fed back into the plant for treatment following the wet weather flow event.
Separate anoxic zone with two 9 kW submerged mixers in biological reactors and internal
mixed liquor recycle up to 2 x average flow) to increase denitrification and total nitrogen
removal.
Low level connection between biological reactors to provide up to 4 ML additional storage
capacity during high flow events.
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Increased capacity of anaerobic sludge stabilization reactor 50 per cent (currently undersized)
by providing a 1.2 m high concrete perimeter wall with improved supernatant withdrawal
facilities.
Modifications to the existing land based solids handling facilities involving Geobags (ie sludge
dewatering and stabilization) and solar drying pans (sludge drying and biosolids stockpiling) to
optimize performance and increase capacity with lower solids mechanical handling power and
costs. A new bunded and lined area will be provided for four larger Geobags (ie 60 per cent of
total Geobag capacity). The upgraded capacity of the existing land-based solids handling
areas will enable long-term sustainable solids management for both average and wet year
conditions.
Additional 8900 m2 area of drying pans for solar drying during prolonged wet periods of greater
than one year (ie contingency provision).
Refer attached site layout plan of proposed works and the proposed bypass pipework.
2.2 Cost of works and application fee
Cost of works Application fee
$2.75 Million $27,500.00
2.3 Proposed dates
Start construction: Month, Year Start operation: Month, Year
July 2013 Operation of upgraded components of the works will be staged as upgrade will be occurring whilst plant is still operational and treating effluent under licence CL67896. Year 1 (2012-2013) Sludge dewatering and drying bed works Year 2 (2013-2014) Inlet works, Biological Nutrient Removal components, changes to Biological reactors 1 and 2. Year 3 (2014-2015) civil works – walkways within biological reactors Year 4 (2015-2016) – Raise anaerobic digester and final process control and instrumentation Year 5 (2016 -2017) – Final Western Drying pan instillation
3. APPROVALS
3.1 Need for works approval
Schedule type Act section that applies
A03 19A (1c),
List any exemptions that apply: section of the Regulations
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3.2 Planning and other approvals
Planning Zone Type of approval required
PUZ1 NA
Approving authority Approval received or pending
BASS Coast Shire council
3.3 Existing EPA approvals (if any)
List any EPA documents held
CL67896, 30A approval 3005601
4. ENVIRONMENT AND COMMUNITY
4.1 Track record
CL67896 2011/2012 annual performance statement reveals noncompliance with condition DW2.4 for the following breaches, exceeded maximum daily discharge 3 times due to increased inflow from wet weather event, breach of annual daily mean limit, breach of annual median value for BOD. All breaches relate to premises 1, Cowes wastewater treatment plant. Previous non-compliance with licence CL 67896 has resulted in breaches of the daily discharge limit of the mean daily flow rate. In 2011-2012 and 2012-2013 Westernport Water has applied for 2 30A approvals relating to the King Road treatment facility (premises 2). There has been no noncompliance with these 2 approvals. Westernport Water has not had any prosecutions, undertakings or abatement notices issued from the EPA in the last 10 years of records
Report any relevant offences; e.g. indictable and summary offences
NIL
List any enforcement actions related to this site
NIL
4.2 Key environmental considerations
List the main environmental aspects of your proposal
Surface water – Ocean outfall Air quality -odour Greenhouse gas and energy efficiency Groundwater Waste management Noise
4.3 Community engagement
Summarise any public consultation that has been undertaken or planned
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Westernport Water has developed a Communications Plan for the project to engage with the community on the proposed works. During Westernport Water’s Water Plan 3 consultation the upgrade projects was discussed as an item of capital works for the 2013-2018 planning period. Planned communication will include direct engagement with effected neighboring landholders, local environmental groups and the Clean Ocean Foundation who are currently operating in Wonthaggi through a targeted Bass Coast Clean Ocean campaign.
Indicate any issues that have been raised
In accordance with our Communication plan early communication with our Customer Consultation Plan has not raised any significant issues with the proposed plan.
5. PROCESS AND BEST PRACTICE
5.1 Process and technology
Key process steps Key inputs Key outputs Key Controls Bypass of screened and degritted flows during peak wet weather flow event to 16 ML effluent storage
Upgrading and/or extension of bypass pipework from inlet works to effluent storage
Bypass screened and degritted peak flows >12 ML/d to effluent storage (>3 x average 2021 flow) Storage of up to 12 ML of bypass flow in the effluent storage, followed by treatment in the plant when flows recede if required. This will provide treatment of up to 24 ML/d (ie up to 6 x average flow). Protection of biological secondary treatment process from solids washout.
Bypass of influent flows during periods of high level in biological reactors. Continuous influent monitoring (ie S:CAN) of COD and ammonia with provision to bypass plant when influent COD falls below set value during peak wet weather flow events. Monitoring of bypass wastewater quality in 16 ML storage to assess need for treatment prior to discharge to Bass strait outfall.
Continuous activated sludge process with variable aeration reactors and clarifiers, and separate anoxic zone for nitrogen removal
Separate anoxic zone with 2 x 9 kW submerged mixers at the inlet of the existing biological reactors. Low level connection between aeration
Increased treatment capacity up to 8 ML/d. Improve process stability and control Denitrification removal increased to 75%, with
Limit max inflow to 8 ML/d Operate at low ML level to maximises high flow storage capacity. Operate at lower
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reactors. Internal mixed liquor (ML) recycle up to 190 L/s
reduced average effluent total nitrogen of 25 mg/L. Provides up to 4 ML flow attenuation storage capacity in the biological reactors
sludge ages (ie 16 days in winter and 12 days in summer) to achieve lower ML concentration and greater clarifier throughput.
Sludge thickening and stabilization in open anaerobic reactor
Provide 1.2 m high concrete perimeter wall around reactor to increase capacity 50%. Upgrade supernatant removal facility.
Improved sludge thickening and stabilization due to longer sludge retention period. Improved supernatant removal resulting in reduced solids returned to aeration reactors. Makes provision for future covering of reactor.
Thickened solids ~ 2.5% total solids and volatile solids content ~70%
Sludge dewatering and further stabilization in Geobags
Provide up to 6 x 1070 m3 capacity Geobags (including one standby) in lieu of the current 10 x 600 m3). New bunded and lined earthen beds for 4 larger Geobags with permeability up to 10-9 m/s and associated underdrainage.
Increased sludge stabilization and solids content due to longer sludge retention period in Geobags (ie > 1 yr)
Dewatered solids spadeable with no free water, ~17% total solids and volatile solids content ~65%.
Solar drying of dewatered sludge on lined open pans, adjacent to Geobags, thus minimizing solids handling between processes for average year operation.
Provide additional sludge drying pans as contingency for prolonged wet period (ie > 1 yr) (increase of 8900 m2), together with associated drainage collection pipework back to the head of the plant.
Provides long term sustainable management of biosolids
Sludge stockpile Provide nominal 1000 m2 of bunded area for storage of dewatered biosolids (> 3yr storage capacity)
Provides long term sustainable management of biosolids
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5.2 Environmental best practice
Indicate steps taken to determine industry best practice The following recent studies have been undertaken to investigate capacity and process upgrade options at the plant and to develop the overall upgrade strategy:
Cowes Wastewater Treatment Plant - Master Plan report and Functional Design report (KBR),
Jul 2001.
Cowes Wastewater Treatment Plant – Number of studies undertaken by DCM and AWT during
2005-2011, culminating in Draft report (AWT, Mar 2011).
Cowes WWTP Upgrade Strategy 2012 – 2021 (CEE Consultants Pty Ltd, in association with
AWT, April 2012).
The studies involved review of industry practice in Australia and overseas for wastewater treatment and solids handling processes, including:
Influent flow and fine screening.
Biological nutrient removal - common and separate anoxic and aerobic zones, and continuous
and intermittent processes.
Aeration systems - surface aeration and diffuse air.
Sludge stabilisation - anaerobic or aerobic (open or enclosed, mixed and/or heated).
Sludge thickening and dewatering.
Sludge drying.
Explain why waste generation and resource use cannot be avoided or minimised Wastewater contains organic and inorganic matter (both insoluble and soluble) that need to be removed prior to effluent reuse/disposal. This requires energy, primarily for oxidation of soluble organic matter present, and often chemicals to aid solid/liquid separation. Waste products resulting from the wastewater treatment and solids handling processes are:
screenings and grit (dewatering and washing equipment).
biosolids (anaerobic stabilisation, dewatering and drying).
gaseous emissions from the biological processes.
Screenings and grit are solids removed from wastewater (ie not generated) and consist of: screenings: solids > 3 mm and grit: solids > 0.3 mm. The screenings and grit are washed to reduce the organic content and dewatered to reduce the water content and volume. Biosolids are a byproduct of the biological secondary process and consist of organic solids (new cell matter) produced by the oxidation of soluble organic matter (oxygen demanding substances) present in the wastewater and the remaining inorganic solids still present in the wastewater after the preliminary treatment. At the Cowes WWTP the biosolids are extensively stabilized and dewatered in a three stage process involving anaerobic digestion, dewatering in Geobags and natural air drying in solar drying beds/pans. These three processes remove most of the organic matter (ie reduce the volatile solids content from 88% down to ~30%) and the moisture content form 0.5% down to ~30%, prior to onsite stockpiling for 3 years followed by beneficial reuse on adjacent land.
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Carbon dioxide is the primary gaseous emission and is produced in the metabolic conversion of soluble organic matter present in the wastewater to new cells. Methane and carbon dioxide are also produced in the anaerobic/aerobic stabilisation of biosolids during the three solids processing steps. Resources used in the wastewater treatment and solids handling processes are:
Electrical power for pumps and equipment throughout the plant (particularly aeration equipment
for oxidation of organic matter in the wastewater)
Recycled water for washing and washdown.
Diesel for land based solids handling processes
Geobags for storage of biosolids during the dewatering process
Sand for drainage layer during biosolids dewatering.
Chemicals are not used for normal operation of the solid/liquid separation processes.
Explain options considered and why this process is considered best practice Biological Reactor options Biological reactor configurations options A separate anoxic biological reactor was selected with a nominal 30% overall anoxic fraction (industry range 25% to 35%). Separate nitrification (aeration) and denitrification (anoxic) reactors are considered best practice. The principal advantages of separate nitrification and denitrification reactors are:
Optimum nitrification due to improved ML suspension and better control of aeration demand,
resulting in reduced residual ammonia in the effluent and reduced chlorine demand for
disinfection
More guaranteed denitrification performance
Improved process stability
Lower power required
Lower alkalinity demand.
The existing combined nitrification/denitrification reactor configuration has resulted in unstable
operation at times. Its primary advantage is lower capital cost.
Biological reactor options Modifying the existing aerobic reactor TK1 to achieve separate anoxic/aerobic zones using dividing curtain/wall and retaining aerobic zone in TK2 was selected as it maximizes use of existing facilities, has the lowest capital and provides up to 4 ML storage capacity for high flows. Providing new biological reactor facilities (i.e. both anoxic and aerobic zones, complete with fine bubble diffused air system) is also considered best practice. This option offers annual power cost savings of up to 30 per cent due to more efficient oxygen dissolution, however this saving does not offset the significant capital cost of about $10 million for a 6 ML/d plant (excluding clarifiers) and the associated substantial resources and energy required to construct.
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ML pumping (internal recycle) options Providing internal mixed liquor (ML) recycling was selected to increase the scope for denitrification.
This option enables the return activated sludge (RAS) flow to be decreased which increases the
clarifier capacity.
Secondary clarifier options Continuous biological processes involving separate biological reactors and clarifiers are considered best practice. They offer superior performance and stability over intermittent aeration and decant systems. Maximizing the capacity of the existing two 14 m dia clarifiers was selected as this makes best use of the existing facilities by maintaining the mixed liquor solids concentration (MLSS) at <3800 mg/L in order to enable the existing peak ML flow of 170 L/s to be maintained and still limit the peak solids flux to < 7.5 kg SS/m2.hr (system capacity). This option was selected as it maximises use of existing facilities and differs high capital expenditure until post 2021.
Options to provide additional clarifier units are expensive and were differed at this stage.
Wet weather flows options Best practice for sizing treatment process capacities are:
Preliminary treatment (ie screening and grit removal) > 5 times average flow
Secondary and tertiary treatment - 2.5 to 3.5 times average flows.
Effluent disinfection – all flow.
The selected option involves operating the existing bioreactors (TK1 and TK2) to treat influent flows up to 8 ML/d and flow attenuating up to a further 4 ML.
When the biological reactor high level is reached excess flow (ie~> 12 ML/d) is bypassed to the 16 ML effluent storage and then either fed back to the plant for treatment following the wet weather flow event or disinfected and discharged with the plant effluent if the quality is monitored as acceptable. This option maximises use of existing facilities and achieves full biological treatment of all flows up to 3 times average 2021 flow (best practice).
The option of providing a new wet weather flow storage (high level) with capacity of 8 ML to 12 ML to store influent flows >8 to 12 ML/d was differed at this stage due to the high capital cost. This option enables treatment of all influent flows up to 5 times average flow (i.e. expected peak wet weather flow), by providing flow attenuation storage at the head of the plant. The stored influent volume would be treated once the influent flow falls below 8 ML/d.
Sludge stabilisation options Increasing the capacity of existing open lined anaerobic digestion reactor (TK3) (50%) was selected as it maximises use of existing facilities, makes provision for future covering of the reactor, has low capital cost and is considered best practice given that the surface is aerated to provide oxidation of methane, hydrogen sulphide and other odourous compounds and odour, and that the Cowes WWTP site is well buffered. The option of providing a new anaerobic digestion facility, involving a covered lagoon/tank with/without mixing/heating, offers improved sludge stabilisation and potential to recover energy and reduce
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greenhouse gases by burning sludge gas recovered, however it has high capital and operating costs and rejected, as was providing lime stabilisation with beneficial reuse of lime sludge which also has high capital and chemical costs.
Sludge dewatering options Continued use of Geobags to dewater and further stabilise the anaerobically digested sludge was selected. This option involves minor additional Geobag capacity, and a new bunded and lined area. The advantages of this option are:
lowest cost sludge dewatering option
produces a product with no free water that can be handled with an excavator (ie spadeable)
No polymer addition required.
Odours emissions mitigated due to solids not coming into direct contact with wind
Well suited to the Cowes WWTP site with adequate land available and well buffered to
sensitive receptors.
Mechanical dewatering options (eg centrifuge or belt filter press) were rejected on the basis of high capital and chemical (polymer) and/or power costs. Sludge drying options Continued use of solar drying pans was selected. This option is well suited to the Cowes WWTP site as it maximises use of the existing pans. No new drying area is required form average and normal wet year conditions. The Cowes WWTP site is well buffered to sensitive receptors (best practice). This option is the lowest cost sludge drying option and was selected. The heat drier option was rejected due to its high capital and energy costs.
5.3 Integrated environmental assessment
Indicate any areas where there are competing environmental demands
Nitrogen removal vs power costs
New biological reactors with diffused air facilities vs long term energy savings and reduced
GHGs
Indicate how you will determine net environmental benefit in these areas
Extent of nitrogen removal The higher the total nitrogen removal achieved and the associated lower effluent nitrogen load, the higher the energy input required, due to the higher internal mixed liquor recycle rates. The following Table shows the theoretical effluent total nitrogen concentration achieved with various internal ML recycle rates. An internal ML recycle rate of 2:1 was selected which is predicted to achieve 75% nitrogen removal (ie effluent average TN of 25 mg/L). The selected recycle rate matches the existing external ML pump rates and thus will enable dual operation and reduced standby pumps. Higher nitrogen removal is not considered necessary for this application given that the effluent is discharges to Bass Strait and reused.
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Item Average 90
th percentile Comment
Influent total N 100 mg/L 110 mg/L
Effluent total N (Theoretical)
Ratio internal ML recycle: Infl. flow Average 90th
percentile
0 45 mg/L 50 mg/L
1:1 33 mg/L 37 mg/L
2:1 25 mg/L 28 mg/L Adopt
3:1 20 mg/L 22 mg/L
8:1 10 mg/L 11 mg/L
New biological reactors with diffused air facilities vs long term energy savings and reduced GHGs New biological reactors fitted with a diffused air system would reduce the average power consumption up to 30%, which would reduce the average power demand up to 28 kW, based on the estimated average power demand of 95 kW for year 2021 operation. This estimated power saving is not considered sufficient to offset the capital, materials and energy costs required to construct a complete new biological facility, and abandon the existing facility that has many years of effective service life left.
5.4 Choice of process and technology
Process or technology Advantages Disadvantages
Refer Section 5.2
5.5 Choice of location and layout
Location or layout Advantages Disadvantages
The upgrade works are located on the existing Cowes WWTP site and are sited on or adjacent to the existing processes and facilities
Maintains existing location of processes and facilities. Operation and maintenance similar to existing.
5.6 Consideration of climate change impacts
Indicate any areas of risk exposure from climate change and uncertainty in environmental condition
Higher intensity and longer duration rainfall events due to increased rainfall variability could result in higher peak wet weather flow events, which would require additional storage and/or wastewater treatment capacity. Higher temperatures are likely to result in increased odour generation in the wastewater reticulation and could require additional odour control measures in the system, including odour treatment at the Cowes WWTP inlet. Rising seawater levels are not considered to have an impact on wastewater flows and loadings
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6. RESOURCES
6.1 Energy
Type of energy use and associated greenhouse gas emission Amount in GJ/yr and tCO2-e
Electricity is used to power all equipment on the site, with the exception of diesel engines used to periodically move dewatered and dried sludge. Approximately 55% of the power demand is for aeration and the remainder primarily for pumping, including the outfall discharge.
Current (year 2011) electricity use was 4.2 GJ/yr and is predicted to increase approx. 29% to 5.4 GJ/yr in year 2021 (note wastewater flow increases 22%).
Type of air emissions Rate or scale of emissions List any class 3 indicators Surface aerators on biological reactors
Local aerosols Nil
Low pressure air on surface of anaerobic sludge reactor
Local odour emission
7.2 Discharge to surface water
Provide reasons for any discharge to water (rather than to sewer or to land)
Not applicable. All wastewater and solids handling facilities are bunded and run-off collected in site catch dam and/or piping and conveyed to plant inlet for treatment. All uncontaminated surface run-off from the site is maintained separate and directed to local watercourse.
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Rate of discharge to water; litres per day Indicate water quality or treatment level Effluent discharge to Bass Strait Year 2011 – Annual volume 1050 ML = 2.9 ML/d average Note ~ 100 ML/yr reused Year 2021 - Annual volume 1270 ML = 3.5 ML/d average Note ~ 150 ML/yr reused
Secondary treatment with effluent disinfection
7.3 Discharge to land
Rate of discharge or deposit to land, Types of waste and level of treatment litres/or tonnes per day e.g. secondary or tertiary
Not applicable
For reuse, demonstrate that the proposal will meet EPA guidelines
See attached Regional EIP for Biosolids reuse in accordance with GEM Biosolids Land Application
Provide the reasons for any discharge to groundwater and indicate segment
Various
7.4 Noise emissions
Hours of operation Noise sources Are they audible at nearby residences?
24/7 Wastewater treatment No
0800 to 1700 Solids handling No
7.5 Greenhouse gas emissions
Scope of emissions Rate or scale of emissions Expected changes over time
1 Wastewater treatment 28% increase (114 t CO2_e/yr) 1 Anaerobic digestion 33% increase (339 t CO2_e/yr)
1 Sludge dewatering - Geobags 73% increase (154 t CO2_e/yr)
1 Sludge drying - Pans 22% increase (116 t CO2_e/yr)
1 Effluent disposal 1% decrease (-1 t CO2_e/yr)
1 All 31% increase (721 t CO2_e/yr)
2 All 20% increase (205 t CO2_e/yr)
3 All 20% increase (39 t CO2_e/yr) Total Scope 1, 2 and 3 All 27% increase (965 t CO2_e/yr)
8. ENVIRONMENTAL MANAGEMENT
8.1 Non-routine operations and climate change impacts
List process upsets that could impact on the environment
Biological process instability – partial loss of nitrification/denitrification, resulting in increased effluent ammonia/total nitrogen concentration/load
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Very high wet weather flow resulting in partial wastewater bypass of biological treatment process and deterioration in effluent quality (eg BOD and nutrients increase) Very poor sludge settling resulting in solids carryover to effluent and deterioration in effluent quality.
List any uncertainty in future environmental conditions that could result in process upsets
Nil
8.2 Separation distances
Proposed buffer distances, in metres Recommended buffer distance, in metres There are 5 residential properties within 1 km of the wastewater treatment plant in Pyramid Rock Road.
1- The closest house is 373m west of the plant.
2- 2nd house is 676m west of the plant 3- 3rd house is 753m north of the plant and a
part of the Westernport Water property 4- 4th house is 771m north of the plant 5- 5th house is 873m North east of the plant 6- There is also an estate within 1km of the
centre of the treatment plant- Wimbledon Heights with 311 serviced properties.
As in accordance with section 10.1 Separation distances for sewerage treatment plant in Recommended separation distance for industrial residual air emissions- EPA Victoria Guideline the separation distance is greater than the 350metres separation requirements for a population size .
8.3 Management system
Explain the system that will be used to manage environmental risk
Westernport Water has an Environmental Management System in accordance with ISO 1400.
8.4 Construction
Identify any environmental risks that will need to be managed during installation
Stormwater run-off
Identify any existing site contamination issues
Nil
Explain how construction will be managed to prevent environmental impacts
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Surface water run-off from the sludge handling area on the eastern side of the site drains to the plant inlet. Surface water run-off from the sludge handling areas on the western part of the site drain to a catch dam and returned to the plant inlet.
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A. ENERGY AND GREENHOUSE GAS EMISSIONS
A1. Energy use and greenhouse gas emissions
Note any existing energy use and greenhouse gas emissions
Refer Section 7.5
Type of energy use or Amount (TJ/year) or Process step greenhouse gas tCO2e/year
Refer Section 7.5
Basis for numbers
Extensive plant monitoring data, NGER (measurement) Technical guidelines 2009 and CEE P/L GHG emission model
A2. Best practice energy and greenhouse gas management
Outline the steps taken to identify best practice energy and greenhouse gas management
Refer Section 5
Summarise the options considered to avoid or minimise greenhouse gas emissions
Refer Section 5
Explain why the chosen option is best practice
Refer Section 5
B. WATER
B1. Water use
Note any existing water use
Only minor water use and generally recycled water
Process step Type of water use Amount (ML/year)
Refer above
Basis for numbers Plant records
B2. Best practice water management
Outline the steps taken to identify best practice for saving water
NA
Summarise the options considered to avoid or minimise water usage
NA
Explain why the chosen option is best practice
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NA
C. SOLID WASTE
C1. Solid waste generation
Note any existing solid waste generation
Refer Section 6
Process step Type of waste generated Amount (t/year)
Refer Section 6
Basis for numbers
Extensive plant monitoring of volume, flows and loads
C2. Best practice solid waste management
Outline the steps taken to identify best practice for solid waste management
Refer Section 5
Summarise the options considered to avoid or minimise solid waste
Refer Section 5
Explain why the chosen option is best practice
Refer Section 5
Indicate where these wastes will go
Refer Section 6
D. PRESCRIBED INDUSTRIAL WASTE
D1. Prescribed industrial waste generation
Note any existing prescribed industrial waste generation
NA
Process Type of waste Waste category Amount (t/year)
NA
Basis for numbers
NA
D2. Best practice prescribed waste management
Outline the steps taken to identify best practice for prescribed waste
NA
Summarise the options considered to avoid or minimise prescribed waste
NA
Explain why the chosen option is best practice
NA
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Indicate where these wastes will go
NA
E. AIR
E1. Air emissions
Note any existing air emissions
Refer Section 7
Process step Type of air emission* Amount (g/min)
Refer Section 7
*Identify any class 3 indicator emissions
Basis for numbers Refer Section 7
E2. Best practice air emissions management
Outline the steps taken to identify best practice# for air emissions
Summarise the options considered to avoid or minimise air emissions Refer Section 5 Explain why the chosen option is best practice# Refer Section 5 #For class 3 indicator emissions assess against maximum extent achievable
E3. Impact on air quality
Predicted maximum
concentration (project) Background concentration
Overall, odour emissions from the plant are not expected to increase, due to greater stabilization of sludge produced and containment of sludge in Geobags prior to solar drying on pans.
The primary factors controlling the rate of odour
emissions from sludge processing facilities are: 1. Degree of sludge stabilisation achieved (eg as
measured in terms of volatile solids content) 2. Moisture content of the sludge (the higher the
moisture content the greater the odour emission)
3. Rate of air transfer across the surface of the sludge (ie the higher the air speed the greater the shear force and the greater the stripping action of odours from the sludge).
Increased dewatering and stabilisation of sludge is
predicted with the increased capacity of the
anaerobic digester and Geobag facilities at the
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Cowes WWTP due to: 1. 50% increase in anaerobic digester capacity.
This is expected to reduce the volatile solids content in the digested sludge ex the anaerobic digester from the current average of 71%VS down to 70% VS
2. Increased storage capacity in Geobags. This will enable > 1 year storage time for further dewatering and stabilization, which is expected to increase the dewatered solids content from the present average value of 15% TS up to 20% TS, and reduce the dewatered volatile solids level ex the Geobags from the current average of 68%VS down to 65% VS.
The provision of a thick dried scum cover over the
surface of the anaerobic sludge reactor and
containing the sludge within the Geobags during
the dewatering and stabilisation stages prevents
direct wind action on the sludge, thus minimising
odour emissions.
Experience at Cowes WWTP indicates that there
has been a significant improvement in odour
levels in the immediate vicinity of the Geobags
since their installation.
Similar experiences have been observed at
numerous anaerobic sludge lagoon facilities
throughout Australia.
Predicted maximum
concentration (total)^
No quantitative odour monitoring has been undertaken, however as no odour complaints have been
received relating to the Cowes WWTP site, the maximum odour concentration is assumed to be less
than the design criteria for no odour complaints at the nearest sensitive receptor. ^Where any predicted concentrations are above the design criteria, provide a risk assessment. Assess any emissions that could impact on regional air quality.
F. WATER
F1. Water discharges
Note any existing water discharges
Refer Section 7
Process step Type of water discharge Flowrate (L/day)
Refer Section 7
Application form for EPA works approval
21
Basis for numbers
Historical daily effluent flow data
F2. Best practice water management
Outline the steps taken to identify best practice for discharge to water
Refer Section 5
Summarise the options considered to avoid or minimise water discharges
Refer Section 5
Explain why the chosen option is best practice
F3. Impact on waterway
Indicator Maximum concentration Median concentration (mg/L)
NA
Water quality objective^
NA ^Where any predicted concentrations are above the objectives, provide a mixing zone assessment
G. LAND AND GROUNDWATER
G1. Discharge or deposit to land
Note any existing discharge or deposit to land
Please see attached hydrological study on current groundwater at the site. The proposed works are not expected to have any significant impacts as the main source of potential impacts will be the storage of biosolids in new drying pan area. The proposed storage areas for wet years will have an impermeable clay lined base with recovery drains for run off collection.
Process step Type of discharge Flow rate (L/day)
NA
Or Type of waste Amount (t/year)
Basis for numbers
G2. Best practice land and groundwater management
Outline the steps taken to identify best practice in discharge or deposit to land
NA
Summarise the options considered to avoid or minimise discharge to land
Application form for EPA works approval
22
NA
For landfills, demonstrate best practice siting and design
NA
Explain why the chosen option is best practice NA
G3. Impact on land and groundwater
Provide a land capability assessment
NA
Groundwater Indicator Predicted Concentration Water quality objective^
NA
^Where any predicted concentrations are above the objectives, provide an attenuation zone assessment
Assess any impacts on the level of the water table
Groundwater salinity levels are variable across the site (range in TDS from 1,408 – 14,720; Segment B to Segment D) and are particularly high to the west of the site (Segment D) which require ongoing monitoring and analysis. Due to the typically poor groundwater quality at the site, there is limited beneficial use of groundwater in the area. The identified beneficial uses include: discharge of groundwater to Salt Water Creek (relatively small groundwater discharge volumes due to the fact the Creek only flows part of the year following rainfall) and potential groundwater use for livestock drinking on surrounding farms. Based on the monitoring data to date background groundwater quality has not been depleted further from the existing background levels.
H. NOISE EMISSIONS
H1. Noise emissions
Process step Source/type of emission Sound power level (dBA)
Refer Section 7
Basis for numbers
H2. Best practice noise management
Outline the steps taken to identify best practice for noise emissions
Refer Section 5
Summarise the options considered to avoid or minimise noise emissions
Refer Section 5
Explain why the chosen option is best practice
Application form for EPA works approval
23
Refer Section 5
H3. Noise impact
Location of Noise levels Existing noise Background receptor(s) from project^ levels (site)^ noise level^
Total noise level^ Noise limit^
^dBA for each of day, evening and night where relevant. Where existing site noise is above the limit, provide a noise reduction plan.
I. ENVIRONMENTAL MANAGEMENT
I1. Non routine operations
Outline the steps taken to identify potential process upsets or failures
As a part of the Westernport Water Environmental Management System aspects and risk in the operation of the plant are registered and the appropriate controls applied. The Cowes wastewater treatment plant has also recently undertaken a HACCP assessment to identify the critical control points in the operation of the plant and compliance with the licence which has fed into the aspects and Impacts register.
Outline approach to identifying best practice in managing these environmental risks
The following have been or are proposed to be undertaken:
Retained specialist process engineers to review process operations and advise on operating
procedures during recent process upsets.
Retained specialist operations engineers to prepare revised operations manual
Additional wastewater and process monitoring equipment has or is being installed, including
S:CAN continuous influent monitoring.
Type of process upset Potential environmental Measures to reduce
impact likelihood and impact
Partial or complete loss of nitrification
Deterioration in effluent quality discharged to Bass Strait
Provide standby aeration equipment and improved dissolved oxygen control
Partial or complete loss of denitrification
Deterioration in effluent quality discharged to Bass Strait
Provide separate anoxic zone
Solids washout of biological process
Deterioration in effluent quality discharged to Bass Strait
Limit maximum flow to secondary system and solids load to clarifiers
Explain why the buffer distance to residents is acceptable
Westernport Water Cowes Wastewater Treatment Plant Upgrade
EPA Works Approval Application
Supplementary Information
1. Site Locality Plan Page 26 2. Proposed Upgrade site Plan Page 27 3. Proposed stormwater bypass Page 28 4. Hydrological Assessment CWWTP Page 29 5. Draft Regional Biosolids EIP Page 41 6. Mixing Zone study and marine assessment Page 70
15
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R i s in g m a in n o t s h o wn 'A s C o n s tr u c t e d '
11/12/2012 Scale: 1:10734
16 ML effluent storage
Biological reactors
Inlet works
PS
PS
New plant bypass
Outfall to Bass Strait Existing pipework
Return Line
Proposed New Bypass Drawing
Appendix 3: Buffer distance 1km from inlet works
There are 5 residential properties within 1 km of the wastewater treatment plant in Pyramid Rock Road.
1- The closest house is 373m west of the plant. 2- 2nd house is 676m west of the plant 3- 3rd house is 753m north of the plant and a part of the Westernport Water property 4- 4th house is 771m north of the plant 5- 5th house is 873m North east of the plant 6- There is also an estate within 1km of the centre of the treatment plant- Wimbledon Heights with 311 serviced properties.
Based on analysis from the groundwater monitoring program to date, there is no confirmed contamination to groundwater occurring from activities carried out at the Cowes Wastewater Treatment Plant. Furthermore, controls are in place to ensure leakage and runoff from stockpiles and sludge drying bags are contained on site (as much as practical) or directed back to the treatment plant. Groundwater salinity levels are variable across the site (range in TDS from 1,408 – 14,720; Segment B to Segment D) and are particularly high to the west of the site (Segment D) which require ongoing monitoring and analysis. Due to the typically poor groundwater quality at the site, there is limited beneficial use of groundwater in the area. The identified beneficial uses include: discharge of groundwater to Salt Water Creek (relatively small groundwater discharge volumes due to the fact the Creek only flows part of the year following rainfall) and potential groundwater use for livestock drinking on surrounding farms (although this has not been confirmed based on analysis of bores registered with the DSE). Based on the monitoring data to date background groundwater quality has not been depleted further from the existing background levels.
2. Introduction
This report provides a summary of the hydrogeological assessment, and further the risk to groundwater quality and the beneficial users of groundwater from activities carried out at the Wastewater Treatment Plant on Phillip Island. This assessment is required under the State Environment Protection Policy (Groundwaters of Victoria, 1970) as part of the works approval process for upgrade of the Cowes Wastewater Treatment Plant.
3. Wastewater Treatment Plant Site Description This section provides background information about the hydrogeology of the site, highlighting potential areas for groundwater contamination and assists to build a conceptual model in order to determine risks to groundwater quality and the potential impacts on the beneficial users of groundwater.
3.1 Site Details- Potential Sources for Groundwater Contamination
The Wastewater Treatment Plant (WWTP) on Phillip Island is situated on Pyramid Rock Road, approximately 3 km from Cowes. The site is located in a small valley, with land rising gently to the east and more steeply to the west. A small marshy area occurs to the north of the site near the corner of Ventnor Road and Pyramid Rock Road. The treatment plant receives effluent from Cowes and other townships on Phillip Island. The wastewater processing activities involve activated sludge treatment (digestion) and clarification, with sludge produced from the clarifiers being returned to a treatment tank for further digestion. The final sludge is placed in drying pans prior for application to land on-site or stockpiling. Liquid from the drying beds is also returned to the treatment tanks. Treated wastewater is stored in 14 ML lagoon, where wastewater is used to irrigate woodlots on site and some is then redirected through a duel media filter and on to the Recycled Water Treatment Plant (RWTP) to produce Class A recycled water for distribution to residential estates in the Cowes area and for irrigation of recreational reserves and the Phillip island Golf Club. Excess wastewater is discharged to the Bass Strait at Pyramid Rock. Runoff generated within the WWTP area is trapped by a series of drains and fed back into the treatment process. An emergency overflow (bunded) area has also been constructed to trap wastewater in the event of an overtopping of the treatment facilities. The area also drains back to a sump there captured wastewater is returned to the activated sludge tanks. The site where these activities are undertaken is shown as the hatched area in green in Figure 1.
3.2 Hydrogeology of the Site
2.2.1 Geology The geology of Phillip Island consists of Tertiary age basalts of the Older Volcanics Formation overlain by Quaternary Alluvium and fluvial sediments (Geological Survey of Victoria). The basaltic rocks form prominent ridges, with the alluvium primarily deposited in low lying areas and along watercourses. The basalts consist of sheet like units often separated by soil profiles produced from exposure and weathering. Joint sets are commonly well developed, with vertical jointing leaving a columnar appearance. The basalts are commonly weathered and form clay layers several metres in thickness (Coffey Partners International Pty Ltd, 1996). 2.2.2 Hydrogeology The geology noted above is likely to form multi layered aquifer systems, comprising the unconfined water table aquifer in alluvial sequences and a number of unconfined to confined aquifers within fractures of the Older Volcanic basalts.
In the fractured rock (Older Volcanic basalts), water infiltrates through joints and fissures. Water contained within fractures not in direct contact with the atmosphere becomes pressured by water infiltrating through recharge zones, forming confined systems driven by pressure head. It is possible different fracture systems will have different pressure heads forming a multilayered confined aquifer system (Coffey Partners International Pty Ltd, 1996). This conceptual model of the sites local hydrogeology is based on groundwater levels and
groundwater quality data collected from 2005 to present as part of Westernport Water’s
groundwater monitoring program. All of the bores monitored by Westernport Water have
been drilled to depths of < 10.3 m and are expected to reflect the unconfined water table
aquifer, due to the seasonally fluctuating groundwater levels and the relatively shallow
depth of the bores.
2.2.3 Groundwater Flow Direction, Recharge and Discharge Areas Recharge areas are likely to be through relatively fresh basalt fractures, rather than weathered areas due to their inherent higher clay contents. Discharge areas are expected to occur in low lying areas, local depressions and watercourses. Salt Water Creek is the nearest ephemeral waterway (only flows part of the year following rainfall) and is located approximately 300 m to the north of the area where the effluent is treated and biosolid/s are or have been stockpiled (refer to Figure 1). Generally groundwater flow within the unconfined aquifer is expected to mimic topography
and flow from the south east to the north-west. Groundwater recharge occurs to locally to
the south-west, where groundwater levels show considerable fluctuation and the
groundwater quality is fresher (has lower TDS). Some groundwater is expected to
discharge into Salt Water Creek, this is due to shallow groundwater levels observed (about
1 m below ground level-refer Figure 4 Bore CGB8) proximal to the creek near the dam.
However, due to the generally low permeability of the soils and the fact that Salt Water
Creek only flows for part of the year following heavy rainfall- groundwater is not expected to
contribute a large volume of flow to Salt Water Creek.
3.3 Surrounding Groundwater Bores
Figure 1 show all of the registered bores within 2.5 km of the treatment plant site and the
bore details are listed in the table below (Victorian Data Warehouse, accessed
24/12/2012). A summary of the bore details shown in Figure 1 is depicted below. Largely,
all of the bores identified are observation bores with incomplete information. Bore 87996 is
screened from 70 – 76 m depth in a deeper aquifer and does not access the water table
aquifer, which is where contamination is most likely to occur from the site activities.
Surrounding land use where these bore are located is largely broad acre (unirrigated)
farming including grazing, dairying and cropping.
Bore ID Use Salinity TDS mg/L
Depth (m)
BORE 87996 Not known- private bore 76.0
BORE 87991 DSE Observation Bore 1962-2,340 5.2
BORE 87990 DSE Observation Bore 1956-7,930 not known
BORE 87998 DSE Observation Bore 1966-2,820 not known
BORE 119076 DSE Observation Bore not known
BORE 119078 DSE Observation Bore 19.00
BORE 118800 DSE Observation Bore not known
BORE 119079 DSE Observation Bore 11.00
BORE 119081 DSE Observation Bore 5.00
BORE 119080 DSE Observation Bore 17.40
BORE 119076 DSE Observation Bore Not known
Figure 1: Overview of the Cowes WWTP. The green area indicates the property owned by Westernport Water. The hatched area indicates the general area for potential groundwater contamination. The map shows all Bore sites registered with the DSE (refer to Table 1 for available bore information)
4. Segment Classification on Groundwater Quality -Cowes WWTP The groundwater environment is divided into segments that are defined by the background level of Total Dissolved Solids (TDS, a measure of salinity) in the groundwater. Westernport Water is required to classify the groundwater (in any aquifer/s identified at the site) based on these segments using as many sources of information that are available, including variable spatial and temporal information. 3.1 Phillip Island Groundwater Salinity Regionally, the Victorian Data Warehouse classifies the groundwater environment on Phillip Island as Segment B for the water table aquifer and Segment C for the Lower Tertiary Aquifer on Phillip Island. These TDS ranges are shown in the table below.
Aquifer Segment TDS Range
Water Table Aquifer B 1001 – 3,500
Lower Tertiary Aquifer C 3,501 – 13,000
3.2 Groundwater Salinity at the Cowes WWTP Locally at the treatment plant site, it is expected that only the water table aquifer has been encountered due to shallow depths of the observation bores and the seasonal fluctuation observed in the groundwater levels (refer to Figure 4). Locally, the groundwater in the area is typically saline and ranges in TDS from 1408 – 14,720. The locations of the observation bores are shown in Figure 2 and the trends in salinity (TDS) are shown in Figure 3. Salinity levels observed in the monitoring bores fluctuate, however there is no continual increasing trend (refer Figure 3). This indicates that there has not been any further contamination of groundwater (from existing background levels) from the site activities at the Cowes WWTP. Monitoring bores CGB5 and CGB6 require further analysis due to the high salinity levels observed, which will be carried out as part of the ongoing groundwater monitoring program. Based on mean salinity data, the groundwater quality in the (unconfined) water table at the Cowes WWTP is classified as segments from B - D (refer to the table below).
Bore ID
Mean TDS (mg/L) Segment
CGB1 2240 B
CGB2 5184 C
CGB3 2496 B
CGB4 1088 B
CGB5 8320 C
CGB6 14720 D
CGB7 6400 C
CGB8 11200 C
CGB9 1408 B
CGB10 9600 C
Figure 2: Salinity distribution based on mean TDS values from the monitoring bores at the Cowes WWTP.
Figure 3: Tends in salinity from monitoring bores at the Cowes WWTP.
Figure 4: Groundwater Levels from monitoring bores at the Cowes WWTP.
5. Beneficial Uses to be Protected: Based on the surrounding land use noted in Section 2.3, the Segments identified in Section 3, and in taking a precautionary approach, the following beneficial uses of groundwater are identified for the area:
Maintenance of ecosystems- minor contributions of groundwater flow to Salt Water Creek
Stock Watering- Although not determined from the Victorian Data Warehouse, due to the surrounding land use it is possible that groundwater may be used for stock watering. Note: groundwater is not used for agricultural irrigation as there was not any irrigation infrastructure/practices observed on surrounding farms.
The indicators and objectives of the SEPP- Groundwaters of Victoria are shown in the table below.
Beneficial Use Indicators Objectives
Maintenance of Ecosystems Specified in SEPP for protection of surface waters*
Groundwater shall not cause receiving waters to be affected to the extent that the level of any water quality indicator is greater than the level of that indicator specified in the SEPP for surface water protection
Agricultural water supply: stock watering
Those specified in the Australian Water Quality Guidelines for Fresh and Marine Waters
Groundwater shall not be affected to the extent that the level of any water quality indicator is greater than the level of that indicator specified for livestock in the Australian Water Quality Guidelines for Fresh and Marine Waters
In accordance with the SEPP –Groundwaters of Victoria (PART IV, 10, (2)), Groundwater quality indicators and objectives will apply to groundwater except where:
(c) The background level of a groundwater quality indicator is greater than the objective, in which case in which case the background level will become the objective
The background salinity of Salt Water Creek exceeds those set out in the SEPP for Protection of Surface Waters (which is 500 electrical conductivity for the Westernport region). However, the current program that monitors water quality in salt water creek upstream and downstream of the treatment plant indicates that there is no further depletion in water quality from the exiting background levels. The groundwater quality, particularly groundwater salinity is variable across the site and it is therefore the difficult to determine if the water quality indicators exceed those set out in the Australian Water Quality Guidelines for Fresh and Marine Waters for livestock drinking. However, it can be concluded that based on the groundwater monitoring to date that no increase in salinity is observed from background levels. A summary of the Segments and beneficial uses for groundwater quality based on salinity is provided below.
Beneficial Uses Segments (mg/L TDS)
A1 (0 – 500)
A2 (501 – 1,000)
B (1,001- 3,500)
C (3,501 -13,000)
D (> 13,000)
1. Maintenance of ecosystems
2. Potable water supply:
Desirable
Acceptable
3. Potable mineral water supply
4. Agriculture, parks and gardens
5. Stock watering
6. Industrial water use
7. Primary contact recreation
8. Buildings and structures
References Coffee Partners International Pty Ltd (1996) Phillip Island Wastewater Treatment Plant Groundwater Monitoring Program, Report No. E3510/1-AE The Geological Survey of Victoria. Queenscliff 1:250,000 geological map sheet, 1971. State Environment Protection Policy (SEPP)- Groundwaters of Victoria- Environment Protection Act 1970 Victorian Data Warehouse, accessed 24/12/2012 http://www.vicwaterdata.net/vicwaterdata/home.aspx
1. Introduction and background The Cowes Wastewater Treatment Plant (CWWTP) is located at the south-eastern corner of
Ventnor Beach Road and Pyramid Rock Road, Phillip Island; situated on 65.34 hectares of
land described as Lots 1 & 2 PS113496 Parish of Phillip Island. The CWWTP operates
under EPA Environmental Licence CL67896 issued 23 June 2010.
The CWWTP predominantly receives raw sewage from San Remo and from the developed
areas on Phillip Island. The CWWTP uses Activated Sludge / Extended Aeration processes,
which result in two final products - effluent and sludge. Currently the sludge is dewatered
and dried using geobags prior to being transported, sun-dried and stockpiled on purpose
built beds as biosolids. Further drying and conditioning occurs over a number of years.
The Corporations EPA licence (CL67896) also specifies the following;
“Discharge to Land requirements
DL4 Deposit of biosolids to land must not adversely affect the land.” (p4)
2. Roles and responsibilities Production, management and use of biosolids comprise the three main components of
biosolids management.
The following parties for the Regional EIP for Biosolids Management undertake these key
roles and responsibilities:
The Supplier of biosolids is Westernport Water.
The end users will be the agricultural landowners on Phillip Island.
This Regional EIP details the roles and responsibilities of parties involved in the
management of land based application of biosolids.
2.1 Westernport Water
Westernport Water is the bulk supplier of the treated biosolids. Westernport Water is
responsible for:
Ensuring the Regional EIP is endorsed by EPA complies with the EPA Publication, GEM Biosolids Land Application;
Ensuring end users of biosolids comply with relevant requirements for the grade of biosolids supplied;
Ensure biosolids meet the biosolids classification required for intended end use;
Keep a register of biosolids scheme, including site location, quality, quantity and use of supplied biosolids; and
Provide data and records of biosolids use to EPA annually.
2.2 Commercial Customers
Ensure site and scheme is managed in accordance with the GEM Biosolids Land Application;
Adhere to requirements within this Regional EIP;
Assess site suitability for biosolids application; and
Keep records of application details.
2.3 EPA Victoria
The EPA is responsible for the approval of this Regional EIP. They provide formal
agreement that the project is environmentally sustainable, provided all the documentation is
complied with.
EPA is also responsible for:
Administering the Guidelines and to ensure for scheme compliance.
Audit and review the effectiveness of the Guidelines to ensure developments are in best practice for biosolids land application use in Australia and overseas are reflected in the Guidelines.
Produce technical supplements for the Guidelines where additional guidance on interpretation of requirements is required.
3. Biosolids Description Biosolids are classified based on two independent factors within the EPA Guidelines GEM:
Biosolids Land Application, the contaminant concentrations in the biosolids and the
microbiological quality post treatment. The classifications within these factors are:
1) Contaminant Grade (C1 or C2) based on biosolids contaminant concentrations
2) Treatment Grade (T1, T2 or T3) based on the treatment technology utilised,
microbiological criteria and measures used to inhibit bacterial regrowth, vector
attraction (such as insects or vermin) and odour.
Unrestricted bioslids achieve both C1 and T1 classifications, whereas restricted grade
material (C2/T1, C1/T2-etc) requires land application management controls to ensure
protection of the environment, public health and agriculture.
The Contaminant Grade is classified as (add here when get final results). Further detail of
the biosolids quality is provided in Section 3.2.
The Treatment Grade at the Cowes WWTP is classified as T3 due to the minimum 60 days
detention in the digester. However, the stockpiled biosolids older than 3 years could classify
as a T1 treatment grade subject to demonstration of minimum regrowth by EPA approved
pathogen testing procedures. These tests are to be carried out in conjunction with the
approval process for this Regional EIP(?).
3.1 Treatment Process of Sludge at the Cowes WWTP
The sludge product from the treatment process is pumped to a 2 ML concrete tank (the
digester) which can be operated under aerobic or anaerobic conditions. The sludge is
settled and clear effluent (Return Activated Sludge or RAS) is decanted back to the aeration
tanks. The thickened, digested, sludge (3 % solids) is then pumped to a series of geobags
installed on drying beds with a sand and clay base. The geobags take approximately 3
months to fill. The drainage from the drying bags is collected and pumped back into the
aeration tanks.
The geobags remain offline for a period of approximately 8 months, after which the biosolids
have dewatered to 15 – 20 % solids.
The dewatered sludge (biosolids) from the geobags is then transported to a stockpile area,
after which it is spread out on purpose built drying pans. After the biosolids have dried in the
sun (add % solids?) it is then stockpiled on site. The biosolids are stockpiled for at least 3
years (from the period of laying the (15 – 20 % solids) biosolids on the drying pans to the
dried biosolids in stockpiles) before any reuse of the product will occur.
The table below depicts the Classifications that apply to the treatment process described
above and details the associated grades and required controls based on the EPA Guideline
GEM; Biosolids Land Application.
Comment [Meg H1]: Find/discuss with EPA monitoring requirements for T1 classification of stockpiled biosolids
Treatment Process Grade Associated Controls
Long-term storage Sludge is
digested, dewatered to > 10
% w/w solids and stored for >
3 years
T1 Product must be stored in
manner that ensures no
recontamination and not
generate offensive odours.
Anaerobic digestion >15 days
at > 35 C or > 60 days at 15
C
T3 Relevant vector attraction
reduction controls and product
that, coupled with management
controls, does not generate
offensive odours. Weed seed
controls may be needed in
landscaping or agricultural
applications.
Aerobic digestion > 40 days
at > 20 C or > 60 days at 15
T3
3.2 Type of use
Based on the Classification of biosolids, the biosolids can be used for the following
purposes:
(to be completed once the classification is confirmed with new results- put in a table)
3.3 Biosolids Quality and Quantity
Quality
- Add all contaminant concentrations (& what is classified as what based on RSCL
values)
- Also add, salinity, pH other properties of the biosolids-any beneficial properties that
farmers may be interested in knowing- potassium contents-etc for soil improvement.
Quantity
The volume of dry biosolids currently stockpiled at the Cowes WWTP is approximately 1,330
tonnes. These biosolids may be classified as T1 (subject to validation process).
On a yearly basis, approximately 500 dry tonnes of biosolids are expected to be produced
(based on 2011/12 yearly production value of 479 dry tonnes)
4. Application Frequency and Scheduling Based on the quality and quantity of biosolids stored at the Cowes WWTP the following
application frequency and scheduling is proposed:
-Get results from Ag-Challenge- based on soil testing results/etc.
This will determine annual usage of biosolids- to include timing/ maturation of existing
biosolids w annual production… ensure long rotations & are not applying biosolids within 4
year period- in any case of re-application need to complete soil analysis to determine
application rates.
5. Transport, storage and distribution system
5.1 Transport
Transport of biosolids is not subject to EPA Prescribed Waste Regulations. However
biosolids are considered a controlled waste under national guidelines.
Transport of biosolids from Westernport Water wastewater treatment plants will follow best
practice measures to ensure there is no spillage, odours, or contamination of the product.
Transport will have;
Transport route with minimal interface with public and minimise impact of transport
on public amenity;
Fully enclosed or sealed tankers or trailers with locks, water-tight seals, and water
proof covers for loads;
Assurance that the vehicle used for transport is not contaminated with wastes that
will impact on the biosolids quality
Cleaning of truck tailgates and tyres prior to leaving sites to avoid carryover or spills
to roads; and
The transport service must have a response plan to ensure rapid clean up of
transport spills. Dry clean up methods are preferred and flushing of spilt biosolids
down drains is prohibited.
5.2 Storage
Biosolids will be stockpiled and stored in a manner to avoid impacts on the beneficial uses of groundwater and surface waters, and avoid generation of offensive odours beyond the site boundary. Stockpiles for medium to long term storage will be stored at the Cowes WWTP, and in accordance with the following requirements:
Stored within a bunded storage area with an impermeable to low permeable base and designed to capture the first flush of contaminated run-off;
Water from bunded storage areas is returned to the treatment plant for treatment and
disposal.
Stockpile areas will be located on a slope less than X per cent;
The Buffer distances (refer Section X) will be adopted
Stockpiles will not be turned or broken up on windy dry days, to minimise off-site odour and dust generation (light watering of stockpiles will be undertaken to control dust generation); and
Where bunding and impermeable base is not practical at the application site, the stockpiles should be located on flat land, stockpiles should be sloped to reduce water penetration, stormwater flow into the storage site should be diverted, increased buffer distances to surface waters may be required and the duration of storage should be minimised
- transport and spreading of biosolids may be managed by WPW to minimise the risk? (TBC)
6. Site locations Insert Map showing all potential agricultural land for beneficial use of biosolids & transport
routes- on the Island/ dependant on soil test results…
Note information to come: Need to define the boundaries of this Regional EIP- very
important to define the boundaries- Include the Webster Property at King Rd– to ensure
there is the option for application at this site.
Owner Site Site Area
(Ha)*
Potential
Biosolids
Application
Volume
(tonnes/Ha)**
Biosolids
Dry matter
Percentage
(%)
Weight of wet
biosolids to be
applied to each
area (Total wet T)
WPW Webster
Property
92
WPW Cowes WWTP
Farm
Subject to
confirmation of
Cd increase to 3
ppm
92
David
McGrath
Middle Farm 8 13.5 92 117
David
McGrath
Ventnor Farm-
Gullaren
8 13.5 92 117
David
McGrath
Rhyll Farm-
Heath Hill
16.5 13.5 92 241
Davies Salt
Contaminated
land***- R&D
31.5 m 2 2.6 kg per
square metre
Total of 78 kg
92 78 kg
Davies Farm
Backbeach Rd-
Carbon Crop
Farming
6.6 13.5 92 87
TOTALS
*site area may be overestimated based on buffer distances and other environment controls
required in individual site plans- or in attached appendix…
**biosolids application volume based on NLAR and CLAR calculations, also not taking into
account environmental controls.
***R&D Project- For Site Remediation of Contaminated Site
7. Biosolids application rate and method
The rate at which biosolids can be applied to land is determined by three factors:
1) The Receiving Soil Contaminant Limits (RSCL)
2) The Contaminant Limiting Application Rate (CLAR) and
3) The Nutrient Loading Application Rate (NLAR)
Although it will vary from site to site, the most common limitation of RSCL is Cadmium, and the most common limitation in NLAR is the rate of nitrogen utilisation. The most limiting factor will be adopted to determine the volume of biosolids that can be applied to land. Refer to the table below for the limiting factors for each of the identified sites.
The application method, specifically the soil incorporation depth will also determine the
volume of biosolids that can be applied to land. For example, if biosolids is incorporated
into the soil with 100 mm depth incorporation (through rotary hoe methods) more biosolids
can be applied than if biosolids were incorporated to 10 mm depth in the soil or simply
applied on the surface (refer to the table below).
Insert Table with Site Details once confirmed- Volume of Land, limiting application rate (note
what the limitation is-i.e. Nitrogen-with 10 mm & 100 mm depth incorporation, and
application method to be utilises//// to be provided by Ag-Challenge when soil results &
biosolids results are available-
Although only the limiting contaminant is listed in the table above, all potential limitations have been considered at each site and the calculations are shown in Appendix 1.
8. Controls
8.1 Biosolids Application Controls
Application Method
Application should include the following measures:
Preferably incorporation into land, achieved through direction injection or surface
application following by incorporation;
Very little if any biosolids should be visible on the surface after injection or
incorporation;
When incorporation of biosolids is not practicable or is contrary to farm practices “i.e.-
no till farming” methods, surface application of biosolids products may be acceptable.
However, any potential risks require careful consideration- in accordance with EPA
Guidelines GEM; Biosolids Land Application
Surface soils should not become compacted as a result of application operations;
and
The application method should ensure biosolids are evenly spread so that maximum
agronomic benefit is obtained
Application Timing
Winter application should be minimised. This is due to low crop nitrogen demand
and high rainfall increases the risk of nitrate leaching, particularly on sandy soils
Application should not occur during high rainfall events, or when application will
coincide with forecasts for heavy rains; and
To avoid nutrient losses, biosolids used in agriculture should be applied to fallow land
as close as possible to the time of sowing, except where other restrictions apply.
8.2 Environment
Land Characteristics
Individual sites will be assessed based on the following characteristics shown in the table
below.
Table X: Land Characteristics and levels of restrictions for biosolids application
Buffer Distances (meters) required for the application sites using T2 or T3 biosolids (delete
which is not relevant) are shown in the table below.
Land Uses Treatment Grade
T2 or C2 T3
Residential Zone, urban areas 50 250
Occupied dwelling 25 50
Surface Waters 50 50
Drinking Water Bores 100 250
Other bores 25 50
Farm dams 25 25
Animal enclosures 10 50
Farm driveways, access roads and fence lines 5 5
Significant native flora and fauna 25 50
Sensitive Areas- highly sensitive ecological,
natural, conservation, cultural or heritage values
worthy of highest levels of protection (gazetted
National or State Parks, Crown nature reserves
for flora and fauna, groundwater recharge
areas, potable water supply catchments, or
aboriginal land of cultural importance)
50 100
8.3 Food safety
-All relevant Food safety practices/ requirements dependent on final confirmed application
sites - TBA
8.4 Occupational Health and Safety
-OH&S records/ etc. applicable to individual sites and will be confirmed when site
investigations are completed.
9. Inspection and management programs The end users of biosolids are to provide operation and maintenance procedures for
biosolids application, storage and distribution.
-If to be contracted by Westernport Water- WPW to develop relevant SOPs for transport,
storage and spreading/distribution of biosolids- can be used as template for farmers who
prefer to use their own equipment…
-Records of maintenance and inspection programs will be kept as a result of the inspection
and management program.
10. Training programs “Restricted Grade” biosolids may contain pathogens and chemical contaminants that require
management, routine OH& S precautions, including:
Education of on-site workers to risks associated with exposure to biosolids
Worker immunisations where appropriate;
Installation of wash basins and the provision of showering facilities;
No food or drink consumption while directly working with biosolids and washing
hands before meals or smoking;
Adopting techniques that minimise the generation of mists and airborne dust, for
example using wet sweeping (not flushing_ techniques rather than dry sweeping,
avoiding high pressure equipment such as air pressure devices; and
Minimising worker access to the site during biosolids application, keeping workers
upwind during application and using protective equipment such as eye protection and
masks if dusts/ aerosols are generated.
Employers should make themselves aware of their occupational health and safety
responsibilities and duties under the Occupational Health and Safety Act 1985. An OH& S
Plan should be prepared, staff trained and safe practices integrated into day to day work
procedures.
11. Monitoring and Reporting
11.1 Monitoring
Nutrients, chemicals and Soil Structure
In addition to the soil monitoring required for determination of the biosolids application rate
(refer to Section X), subsequent soil sampling should be carried out when either:
Mass balance calculations indicate that biosolids have contributed a load that
exceeds 10 per cent of the RSCL since the previous sampling;
Four biosolids applications have been undertaken since the previous sampling; or
20 years have passed since the previous sampling
For Agricultural land uses, ongoing monitoring of parameters such as nutrients and
acidity/alkalinity should be conducted as part of normal farm nutrient/ fertiliser planning and
soil health management programs.
Groundwater Monitoring
Groundwater monitoring will not typically be required for schemes complying with this
Regional EIP, monitoring may need to be undertaken where local conditions and volumes of
use indicate a potential risk to groundwater.
Regional groundwater would be most vulnerable at sites having:
Highly permeable soils or such as coastal dune sands, alluvial deposits or soils with
hydraulic conductivity > 50 mm/h in the most restrictive layer;
Shallow water table for example less than 1.5 – 3 m depth to groundwater;
Less than 60 cm depth to bedrock or clay hard pan
Hydrogeological assessments should be made in accordance with EPA 2006 Publication
Hydrogeological Assessments, Groundwater Quality. Where risks are indicated,
hydrogeological experts should be consulted to assist with the development of appropriate
groundwater monitoring programs according to specific site features and groundwater
vulnerability.
Food Safety Monitoring
Direct testing may need to be undertaken, depending on the risks to food safety. Sampling
and analysis should reflect the identified risks and should be conducted in accordance with
Guidelines for sampling soils, fruits, vegetables and grains for chemical residue testing (NRE
1999#AG0889).
For biosolids applied to agricultural grazing land, a stock monitoring program may need to be
implemented in accordance with the Livestock Diseases Act 1994.
11.2 Record Keeping
Supplier/Producer (Westernport Water) Records
Westernport Water must maintain the following records regardless of biosolids quality:
Batch identification (or for a continuous operation, the biosolids produced between
sampling periods)
Production period;
Contaminant concentrations and batch grade;
Historic trends of contaminant levels;
Treatment process, microbiological testing, stabilisation method and resultant
treatment grade;
Concentrations of nitrogen, phosphorus and other relevant nutrients in biosolids;
Details of incidents and the corrective action taken;
Inspection and maintenance reports;
Quantity (dry tonnes) and solids content of the batch; and
The type of produce produced.
Address of the biosolids application sites, end use and the relevant EIP (this
document?)
Records need to be maintained for at least 10 years in order to analyse trends and
demonstrate ongoing compliance with the objectives in this regional EIP and with the EPA
Guidelines GEM; Biosolids Land Application
End Users
Restricted grade biosolids end users need to maintain the following records:
Source of biosolids, batch identification and date received;
Biosolids classification information from Westernport Water;
Details of application site including: location, name of occupier or owner, area
involved, date of application;
The calculated NLAR;
The concentrations of contaminants in soil prior to biosolids application;
The calculated CLAR;
The application rate and method of application;
The soil pH and salinity;
Monitoring data and analysis of trends in the parameters;
When quality limits are exceeded and the corrective action taken; and
Cross reference to the relevant EIP/ management controls (this document- or to
make an operations manual?)
11.3 Reporting
Westernport Water will provide an annual records of all monitoring programs in accordance
with the GEM; Biosolids Land Application.
12. Emergency Plans In the event on an emergency incident following biosolids use, the user and or/ Westernport
Water must notify the regulatory body. This includes breaches such as:
Breach of RSCLs; or
Violations of food standards (i.e. MRLs or MLs).
Notification should be as soon as practical and include details of testing results, cause and
effect and the corrective and future preventative action being taken (WPW to create a
form/procedure for information and actions).
EPA should be notified of any event or emergency that poses risk to the environment
including: biosolids spill to roads or immediately into adjacent waterways.
Department of Health are to be notified in case of emergency or incident that significantly
increases the risk to public health and food safety.
DSE should be notified in event of an emergency or event that presents a risk to native flora
or fauna, National Parks, conservation reserves or other sensitive land.
13. EIP review A review of this regional EIP will be undertaken after a three year period with analysis of
crop yields to determine the effectiveness of biosolids application to land.
CEE Consultants
Report to: Westernport Water
Cowes Wastewater Treatment Plant
Marine Ecosystem Monitoring Ecology, Water Quality and Ecotoxicity
2012
July 2012
CEE Consultants
“Cowes Wastewater Treatment Plant. Marine ecosystem monitoring. Ecology, water quality and ecotoxicity. July 2012”
Report to:
Mr Stephen Porter, Ms Benita Russell Westernport Water Corporation 2 Boys Home Road Newhaven VIC 3925 Report prepared by: Scott Chidgey, Natalie Calder and Peter Crockett CEE Consultants Pty Ltd PO Box 201 VIC 3121 [email protected]
Westernport Water collects and treats wastewater from a wide area including Phillip Island
and towns on the western shores of Western Port. Much of the collected wastewater is
treated at the Cowes Wastewater Treatment Plant (WTP) on Phillip Island. Class C treated
effluent that is not reused is discharged under EPA licence to Bass Strait at an outlet located
near Jessie Island, approximately 1.8 km north northeast of Pyramid Rock.
Figure 1. Location of Phillip Island outlet
2 COWES WASTEWATER TREATMENT PLANT AND OCEAN DISCHARGE
The Cowes Wastewater Treatment Plant treats all domestic wastewater collected on Phillip
Island to a standard generally compliant with Class B quality using secondary treatment
(biological treatment using activated sludge). A small amount of treated effluent undergoes
tertiary treatment (coagulation, sand filtration and chlorine disinfection) to Class B for reuse
purposes. Most treated effluent is disinfected with chlorine and discharged to Bass Strait via
the shoreline discharge east of Pyramid Rock.
Marine ecosystem monitoring. Ecology, water quality and ecotoxicity 2
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The Cowes WWTP has a treatment capacity of 8.5 ML per day. The average effluent flow in
2011 was 3.4 ML/d. Effluent is stored in a lagoon at the treatment plant and is intermittently
pumped to the ocean outfall. The duration of discharge varies, but is generally less than 10
hours per day.
Reuse of treated wastewater by local sports grounds, golf club and agriculture is presently
approximately 10% of the inflow to the plant. The remainder of the wastewater is discharged
to Bass Strait over a four hour period at night when electricity rates for pumps are lower.
Table 1 shows effluent flows for five other discharges in Victoria. The flows to the Pyramid
Rock outfall are substantially lower than discharges for Melbourne and Geelong but larger
than those in Surf Coast (Lorne and Anglesea) communities.
Table 1. Approximate flows at wastewater outlets in Victoria
Treatment Plant ML/a ML/d
Western Treatment Plant (2008/09) 79205 217
Boags Rocks combined (2008/09) 106522 292
Geelong (2008/09) 18000 49
Phillip Island 1280 3.4
Lorne (Lorne) 350 1.0
Anglesea (Anglesea) 200 0.5
3 REGULATORY BACKGROUND
The discharge of wastewater effluent to the aquatic environment in Victoria requires a
licence from the Environment Protection Authority. The legal framework for EPA to issue
licences are the Environment Protection Act 1970 and State Environment Protection Policy
(Waters of Victoria) 2003.
The Waters of Victoria Policy recognises that Beneficial Uses of Victoria’s aquatic
environment should be protected. Part IV of the Policy lists the protected beneficial uses in
the range of Victoria’s water segments, which include aquatic reserves, wetlands, rivers,
streams, and marine and estuarine segments. The Pyramid Rock wastewater discharge is
within the Open Coast segment of the area covered by the SEPP(WoV). The Beneficial
Uses of the marine environment at Pyramid Rock are:
Aquatic Ecosystems that are:
Largely unmodified
Water Suitable for:
Primary contact recreation
Secondary contact recreation
Aesthetic enjoyment
Indigenous cultural and spiritual values
Non-indigenous cultural and spiritual values
Aquaculture
Industrial and commercial use
Fish, crustaceans and molluscs for human consumption
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The Policy defines environmental quality objectives to protect the listed beneficial uses of a
segment. The Australian and New Zealand Guidelines for Fresh and Marine Water Quality
(2000) form the basis for environmental quality objectives defined within the SEPP(WoV).
The environmental quality objectives relevant to the Pyramid Rock discharge are shown in
Table 2:
Table 2. Environmental quality objectives for Open Coast segment
including Pyramid Rock
Parameter Protection Level Definition
Aesthetics,
Cultural and
Spiritual
Values
No loss of value
Discharge should not result in loss of aesthetics or
cultural and spiritual values, objectionable odours,
colours, taints, floatables, foam, oil or grease or dirty
water
General
Ecosystem
Protection
99% Ecosystem condition must be maintained to within
99% of reference ecosystem condition
Toxicants
Ammonia
(ammonium)
99% trigger value
0.500mg/L
(ANZECC 2000)
Concentration of ammonia that will protect 99% of
species from toxic effects*
Nutrients and Water Clarity
Phosphorus 75%ile ≤25 µg/L
(Total P) Concentration that will protect ecosystem from
adverse effects (stress) Nitrogen
75%ile≤10 µg/L
(Total N)
*Values derived from ecotoxicity tests on a limited range of organisms under laboratory
conditions
3.1 Monitoring Process
The Policy aims to minimise impacts and environmental risk to these beneficial uses. The
Policy strategy is to revise existing licences to ensure that:
Licences are consistent with the Policy aims;
Licences include a monitoring program to assess the impact of effluent discharges on
beneficial uses; and
Licence holders are implementing plans to reduce impacts of discharges on the
beneficial uses.
The implications of the state Policy and national Guidelines requirements and aims are
monitoring programs to assess the impact of effluent on the local beneficial uses.
3.2 Monitoring environmental risk
Westernport Water’s marine environmental monitoring tasks described in this report were
designed after screening the risks of effluent discharge at Pyramid Rock for the Beneficial
Uses of the marine environment near Pyramid Rock (CEE 2009). This set of initial
monitoring tasks aims to detect the extent of potential effects of the discharge on the key
Beneficial uses in the vicinity of the discharge. The key Beneficial Use in the vicinity of the
discharge was identified as Aquatic Ecosystems that are largely unmodified.
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4 OBJECTIVES OF MONITORING PROGRAM
As discussed above, the State Environment Protection Policy (Waters of Victoria) aims to
minimise impacts and environmental risk to beneficial uses. The key Beneficial Use in the
vicinity of the discharge was identified as Aquatic Ecosystems that are largely unmodified.
The Policy requires that:
Discharge licences are consistent with the Policy aims;
Discharge licences include a monitoring program to assess the impact of effluent
discharges on beneficial uses; and
Discharge licence holders are implementing plans to reduce impacts of discharges
on the beneficial uses.
Hence, Western Port Water requires CEE to:
monitor the marine ecosystem in the vicinity of the Phillip Island discharge;
assess the impact of the Phillip Island effluent discharge on beneficial uses and
advise on measures that may be required to manage the impacts of the discharge on
beneficial uses
The objectives of the program were to undertake three risk-based, marine environmental
tasks that inform the assessment of the effluent discharges on beneficial uses, including:
Ecosystem monitoring to document the extent and impact of the treated effluent
discharge on marine biological communities;
Dilution and dispersion to define the worst case mixing conditions in the vicinity of the
ocean discharge point; and
Effluent toxicity testing.
This is consistent with the Policy requirement for “a monitoring program to assess the impact of the wastewater discharge on beneficial uses” – in this case the beneficial use of aquatic ecosystems.
Marine ecosystem monitoring. Ecology, water quality and ecotoxicity 5
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5 ENVIRONMENTAL CONTEXT - ECOLOGY
The Cowes WWTP discharge is located in the south-west corner of a small cove around 1
km north east of Pyramid Rock (Error! Reference source not found.). This section of
Phillip Island coastline faces south-east and is strongly influenced by ocean swell. Tidal and
wind driven currents are low, but mixing due to wave action may be strong and there may be
locally strong wave driven water currents (rips). The high wave energy nature of this
coastline results in steep beaches, heavily eroded rock platforms and presence of Bull Kelp
(Durvillaea potatorum) along the fringes of intertidal rock platforms.
Figure 2. Cowes WWTP ocean discharge locality and survey area
Aerial photos circa 1990s
5.1 Intertidal habitats
The section of coastline where the outfall is located is a complex mosaic of predominantly
basalt, tuff and agglomerate rock forms. The outlet is located among basalt boulders at the
head of a small cove (Figure 2). Boulders (0.1 to 0.75 m diameter) and low broken rock
platform characterise the intertidal habitat at the head of the cove. An elongate shallow
agglomerate rockpool extends south from the boulders at head of the cove.
A large, flat basalt platform elevated above the high water mark extends approximately 50 m
along the south boundary of the cove. The platform forms the shoreline to the southwest of
the cove. The seaward fringe of the platform drops steeply.
Marine ecosystem monitoring. Ecology, water quality and ecotoxicity 6
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The north shore of the cove comprises a complex series of basalt platforms with channels,
pools and outcrops providing habitats with a wide range of shore levels and wave
exposures. The fringes of this platform are highly dissected. Small bombora are located off
the end of the platform. The platforms drop steeply into the subtidal.
The shoreline to the north of the cove comprises rock platforms at lower shore levels. Wave
energy is attenuated more gradually along these shores and inshore areas are generally well
protected from wave action by the rock platforms further offshore. The wide, flat rock
platforms provide abundant habitat for intertidal marine biota including well protected
intertidal pools and shallows. Sandy beaches are found near the shore in places.
Overall, the physical environment in the vicinity of the Pyramid Rock discharge is
heterogeneous resulting in a wide range of available intertidal habitats within a relatively
small area.
5.2 Intertidal biological conditions
The intertidal biological characteristics are strongly influenced by the physical habitats and
processes in which they occur. Ecological interactions between species are the other major
determinants of the composition of biological assemblages.
Intertidal biological assemblages are characterised by strong zonation depending on shore
height (period of inundation) and wave exposure. The shoreline near the Cowes WWTP
discharge is no exception. Zonation in the area occurs both with shore height (primarily due
to period of inundation but also due to wave exposure) and along shore (primarily due to
wave exposure).
The large basalt platform to the south of the cove has a distinctive biological assemblage.
The fringe of the rock platform just above the low water mark supports algal turf
(predominantly red algae and red coralline algae) with some grazing molluscs. Areas above
this have very sparse cover of algae and grazing molluscs. The pools on top of the platform
and at its nearshore side, filled at high tide by large waves and/or spay, support algae
including Hormosira banksii and limpets. Otherwise the top of the platform is mostly clear of
macroalgae with small Blue Periwinkles (Austrolittorina unifasciata) occupying some
patches. At the low water mark in more exposed areas the large brown algae Durvillaea
potatorum (Bull Kelp) grows abundantly with encrusting coralline red algae. Near the outfall
and in more protected areas generally, D. potatorum is replaced by Phyllospora comosa
(Cray Weed).
Within the cove, on the more protected sections of basalt rock platform both north and south
of the outlet, Phyllospora comosa dominates at the low water mark. In the intertidal, thick red
algal turf grows in the low intertidal, the mid intertidal is dominated by coralline red algae
(Corallina officinalis) and the high intertidal is dominated by grazing limpets in bare space
and Ulvales (ephemeral green algae). Mid-intertidal pools or crevices have some Sargassum
sp. while high-intertidal pools are dominated by H. banksii. In very high intertidal areas which
receive mostly spray Nerites (grazing gastropod molluscs) are abundant.
The boulders and cobbles forming the beach within the cove also have clear zonation of
biological assemblages. The boulders at low shore levels, and the lower sections of larger
boulders, have dense red algal turfs, mid intertidal boulders and boulder sides have dense
Marine ecosystem monitoring. Ecology, water quality and ecotoxicity 7
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Corallina officinalis while high intertidal areas have ephemeral green algae (Ulvales) and
grazing limpets in bare spaces. Nerites (Nerita sp.) are abundant in very high intertidal areas
which receive mostly spray.
Due to the highly heterogeneous nature of physical habitats on the platform north of the
outlet cove the zonation of biological assemblages there is more complex. The fringe of the
platform within the cove is dominated by Phyllospora comosa as discussed above. Beyond
the cove the fringes are dominated by P. comosa where wave exposure is lower and D.
potatorum where wave exposure is higher. The low intertidal fringe of the platform has thick
red algal turf as elsewhere, with C. officinalis in the mid-intertidal.
The top of the platform has a very patchy distribution of biological assemblages. Higher
areas have abundant grazing limpets in bare spaces and ephemeral green algae (Ulvales).
Patch sizes range between less than 1 and greater than 20 square meters. Lower areas
have a mixed algal assemblage including Corallina officinalis, Ulvales and Hormosira banksii
with a range of gastropod molluscs. Lower and wetter areas have almost monospecific cover
of C. officinalis. Pools which retain water at mid-intertidal levels have Sargassum sp. (Brown
Algae) while pools at higher shore levels have H. banksii.
The platforms further north have essentially the same biological assemblages as those
nearer the outlet cove. The intertidal rock platforms cover greater areas however and
patches of different composition are generally larger. High intertidal areas have a mixed
assemblage of Ulva, bare space with grazing limpets and H. banksii. Lower areas have
abundant C. officinalis or mixed algal assemblages grading into turfing red algae and kelps
at the low water mark. Low-shore pools and the low intertidal have cover of mixed algae
including Sargassum sp.
Protected nearshore areas north of the outfall cove have accumulated sand and some
shallow areas have seagrass (Zostera sp. and Amphibolis antarctica).
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6 ECOLOGICAL MONITORING
Ecological monitoring allows the direct assessment of the nature and extent of effects of the
effluent discharge on the Beneficial Use “Aquatic Ecosystems”. The background to
ecological monitoring and the results of the monitoring program at the Phillip Island
discharge location are described in this section.
6.1 Previous monitoring
CEE Consultants previously monitored marine ecological conditions at the Pyramid Rock
wastewater discharge in 1991, 1994, 1995, 1998, 1999 and more recently in 2010. The
surveys used quantitative methods to assess exposure-related wastewater impacts on
intertidal biota including algae and invertebrate communities over space and time (“Intertidal
Biota at Phillip Island Treated Wastewater Discharge – February 1999” and “Mixing Zone
Study - Ecotoxicity, Ecology and Water Quality – 2010”).
The ecological monitoring program focused on abundant known and likely indicators of
effluent effects including the molluscs Siphonaria sp., Turbo sp., Notoacmea sp., and the
algae Ulva (sea lettuce), turfing green algae, coralline red algae, Hormosira banksii
(Neptunes Necklace) and Durvillaea potatorum (Bull Kelp).
Key findings of the 1991-1999 ecological monitoring program included:
No pattern in Siphonaria abundance over time or space suggesting effluent effects;
Turbo abundance was higher nearer the outlet where it was found imbedded in the
dense coralline algal turf on the boulders around the outfall. The localized increase in
abundance was attributed to either or a combination of effluent effects, habitat effects
or an association with coralline red algae. Turbo numbers decreased when effluent
loads decreased suggesting an influence of effluent in close proximity to the outfall.
Notoacmea numbers near the outlet declined over the period of decreasing effluent
loads, but did not show strong spatial patterns in abundance in any survey.
The abundance of Ulva and other green algae (whose abundance usually increase in
the presence of effluent discharges) also declined in concert with decreasing effluent
loads, suggesting a reduced impact on the outfall.
Coralline red algae abundance in the vicinity of the outlet was high in all surveys
suggesting positive effluent effects, however coralline red algae abundance at
reference sites 200 m away was also high.
Hormosira banksii abundance within the cove was low over the period of monitoring,
with higher abundance occurring outside the cove. A negative effect on this species
could not be confirmed but any effect was thought to be restricted to within the cove
itself.
No change in the nearest occurrence of the bull kelp Durvillaea potatorum was
detected during the monitoring program.
The survey in 2010 followed the same general rationale as the previous surveys, but used
quantitative photographic methods that allowed monitoring at more sites during a single low
tide period. The conclusions to the 2010 survey were generally similar to the previous
surveys, suggesting that the characteristics of the marine community, particularly with
respect to indicators of effluent effect, were relatively stable.
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6.2 Ecological monitoring sites – 2012
Ecological conditions were assessed in 2012 using the same quantitative methods and cove
sites as 2010. A total of 19 sites in the April 2012 ecological survey. Conditions at a further
15 photopoints were recorded and assessed for the presence or absence of Durvillaea
potatorum.
The position of the 2012 ecology sites and corresponding sites from 1991-1999 monitoring
program are shown in Table 3 and Figure 3.
Table 3. Ecology Site Details – 1991 to 2012 Ecology Sites – 2010, 2012 1991-1999 sites
Site Details Distance and direction
from outlet Easting Northing
Site Name
Easting Northing
South
S7 58 m SW 345478 5734612
S6 21 m SW 345494 5734646 W1T 345498 5734643
S5 17 m S 345516 5734646 W1 345515 5734625
S4 14 m SW 345502 5734649
S3 13 m S 345508 5734647
S2 Start 10 m S 345513 5734650
Transect End 21 m SE 345520 5734643
S1 Boulder a 6 m S 345512 5734655
Boulders Boulder b 5 m S 345510 5734656
Boulder c 2 m S 345510 5734659
Outlet seaward end of pipe 345510 5734661 Outlet NA NA
shoreward end of pipe 345502 5734670
Nort
h
N1 (Boulder Transect)
Start 10 m NW 345505 5734670 E1 NA NA
End 27 m NW 345514 5734688
N2 44 m NE 345531 5734698 E2 345525 5734710
N3 45 m NE 345538 5734696
N4 55 m NE 345551 5734696 E4 345548 5734677
N5 Start 56 m NE 345561 5734685 E4T 345556 5734660
End 64 m NE 345569 5734687
N6 62 m NE 345563 5734693
N7 71 m E 345578 5734681
N8 74 m E 345577 5734692
N9 82 m E 345585 5734694 E5 345605 5734717
Ref REFN1 98 m NE 345597 5734706
REFN2 107 m NE 345582 5734740
Photo
poin
ts
1 W 26 m SE 345525 5734640
2 W 31 m SE 345529 5734636
3 W 36 m SE 345532 5734633
4 W 38 m SE 345529 5734628
5 W 42 m SE 345532 5734625
6 W 49 m SE 345534 5734618
7 W 56 m S 345532 5734609
8 W 62 m S 345529 5734602
9 W 79 m S 345517 5734582
10 W 85 m S 345514 5734576
11 W 86 m S 345511 5734575
12 W 92 m S 345508 5734569
13 W 94 m S 345503 5734567
14 W 95 m S 345482 5734570
15 W 124 m S 345469 5734544
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Figure 3. Marine ecosystem monitoring sites, 2010 and 2012
6.3 Ecological survey methods
Photographic methods were used to document ecological conditions at the monitoring sites.
6.3.1 Quantitative photographic method
Quantitative point intercept methods were used at sites where quadrats could be placed and
photographed on the rock surface. Between 15 and 25 quadrats measuring 0.3 m by 0.3 m
square were randomly positioned at each site. A digital image was taken of each quadrat for
subsequent point intercept analysis. Other characteristics were noted at each site including:
the position of each site in relation to the outfall, shore height, wave exposure and key
features of the biological assemblage. Panoramic photos were also taken at each site.
Sites were positioned at a range of shore heights and on a range of habitat types due to the
highly heterogeneous nature of the intertidal rock platforms. The nature of each site
determined how the photoquadrats were positioned:
1. At sites where an area of around 5 m2 with continuous physical and biological
features was available quadrats were positioned randomly within that area or patch.
The centre of each site was marked using GPS. At least 15 but generally at 16
photoquadrats or more were collected at each such site;
2. At sites where boulder habitat predominated quadrats were positioned on the tops
and/or sloping sides of boulders; and
3. At sites where consistent habitat and biological features were distributed along a
relatively narrow band (such as the boulders forming the beach within the cove)
transects were established. The end of each transect was marked using GPS. A total
of 25 randomly located quadrats were photographed along the transect.
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Table 4 Details of photoquadrats and survey method at ecology sites
Site Number of
Photoquadrats
South S 7 16
S 6 16
S 5 16
S 4 15
S 3 16
S 2 - Transect on rock platform 16
S 1 (Boulders) 16
Outlet Transect along concrete pipe 16
North N1 - Transect on boulders 25
N 2 16
N 3 16
N 4 16
N 5 - Transect on rock platform 25
N 6 16
N 7 16
N 8 16
N 9 16
North Reference Site 1 16
Site 2 16
6.3.2 Photopoint sites
1. At a further 15 points along the basalt platform to the south of the outlet, GPS
positioned ‘photopoints’ were established to document the distribution of the negative
indicator species Durvillaea potatorum (Bull Kelp) to the south of the cove. A number
of locations where positive or negative indicators were present were also marked
using GPS during the survey.
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Table 5 Categories used in point-intercept analysis Group Category/Species Description/Common Name
Brown Algae Hormosira banksii Neptunes Necklace
Scytosiphon lomentaria(ralfsia) Ralfsia stage
Colpomenia sinuosa Sinuous ballweed
Sargassum sp. Rock weed
Cystophora sp. Rock weed
Filamentous algae on C. officinalis Ectocarp epiphyte on C. officinalis
Red Algae Corallina officinalis
Encrusting Coralline Red Algae
Erect Coralline (other) Erect coralline algae (not C. officinalis)
Red turf
Filamentous algae on C. officinalis Red epiphyte on C. officinalis
filamentous algae on rock
Green Algae Ulvales on Rock Sea lettuce (growing on C. officinalis)
Ulvales on C. officinalis Sea lettuce (growing on rock substrate)
Ulvales on limpet Sea lettuce (growing on Limpets)
Microalgal film on Encrusting coralline algae
Filamentous algae on C. officinalis Green epiphyte on C. officinalis
General Categories Filamentous epiphyte Unidentified Epiphytic algae
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Total phosphorus concentration ranged across the mouth of the cove from 0.19 mg/L
at 55 m from the outfall on the south of the cove to 0.42 mg/L at 64 m from the outfall
on the north side of the cove.
The total phosphorus concentrations indicate that effluent was dispersing northward
and eastward around the cove and across the rock platforms north of the cove.
7.3 Implications of water sampling results
The water sampling results showed that
Ammonia concentrations were below the SEPP trigger value for the effluent quality
and mixing conditions in 12 April 2012
Total nitrogen concentrations on 12 April 2012 were above the SEPP 75 percentile
water quality objective and it is likely that the ambient total nitrogen concentration in
ocean water is naturally relatively high
The total phosphorus concentrations on 12 April 2012 were above the SEPP 75
percentile water quality objective for the effluent quality and mixing conditions at all
sites within the cove and to between 100 and 170 m north of the cove.
7.4 Effluent Dilution
The dilution of effluent in the ambient seawater in and near the cove can be estimated using
(1) the concentration of key chemical constituents in effluent (2) the concentration of key
chemical constituents in seawater and (3) the background concentration of key chemical
constituents in seawater.
The concentration of the key nutrients phosphorus, nitrogen and ammonia on 12 April 2012
are shown in Table 7 and are summarised in Table 8.
Table 8. Summary of effluent and water quality values
Total phosphorus Total nitrogen Ammonia
Effluent, mg/L 9.6 5.5 4.0
Range in seawater, mg/L <0.01 to 0.68 0.07 to 2.3 <0.001 to 0.27
Chosen background, mg/L 0.02 0.1 0.003
The table shows that background concentrations of total phosphorus and ammonia were
substantially lower than the concentrations in effluent. Hence, they are suitable for
estimating effluent dilution in seawater. Total nitrogen concentrations in seawater were less
than two orders less than effluent and therefore cannot reliably be used to estimate dilutions
accurately.
Effluent dilutions in seawater at each site were calculated using the following formula
Effluent dilution in sweater = (Ceffluent-Cmix)/ (Cmix-Cbackground), where
Ceffluent is the concentration of the constituent in effluent
Cmix is the concentration of the constituent in a seawater sample containing effluent
Cbackground is the concentration of the constituent in sweater without effluent
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Table 9. Effluent dilution in sweater samples, 12 April 2012
Location Sample position Distance from
outfall, m Dilution using phosphorus
Dilution using Ammonia Easting northing
Cove 345515 5734655 1 15 15
Cove 345514 5734648 8 22 23
Cove 345524 5734646 13 22 23
Cove 345528 5734652 14 14 14
Cove 345505 5734667 15 63 66
Cove 345518 5734671 15 52 55
Cove 345534 5734654 19 14 14
Cove 345520 5734678 23 45 48
Cove 345534 5734643 23 59 60
Cove 345541 5734647 28 19 19
Cove 345520 5734687 31 22 23
Cove 345540 5734681 35 33 36
Cove 345554 5734647 40 19 19
Cove 345553 5734678 44 47 54
Cove 345538 5734698 48 39 46
Cove 345554 5734688 50 47 50
Cove 345571 5734656 56 24 26
Cove 345563 5734686 57 31 33
Mouth 345556 5734620 55 55 60
Mouth 345574 5734631 64 23 24
Mouth 345609 5734657 94 239 265
Channel 345496 5734634 29 22 26
Channel 345482 5734611 56 26 42
Northeast 345544 5734707 59 63 73
Northeast 345561 5734700 64 55 60
Northeast 345544 5734716 67 67 79
Northeast 345578 5734689 71 239 285
Northeast 345582 5734740 107 318 306
Effluent dilutions are shown in Table 9, which shows:
Similar estimates of effluent dilution for both total phosphorus and ammonia, which
indicates confidence in the dilution estimates;
Minimum dilutions of approximately 15:1 seawater to effluent inside the cove within
20 m of the outlet;
Minimum dilution of approximately 25:1 at the mouth of the cove, 60 m from the
outlet; and
Minimum dilution of approximately 55:1 across the rock platform during the rising
tide, 60 m from the outlet.
The following factors affect effluent dilution in the cove:
Effluent dilution is constrained within the cove at low tide by the limited exchange of
water between through the mouth of the cove and adjacent open waters.
Higher effluent flows will result in lower dilution.
Dilution will be greater during high tide when breaking waves carry water into the
cove through the mouth and waters wash out of the cove across the rock platforms to
the northeast. This process results in fresh sweater water flowing through the cove
and diluting and dispersing effluent.
Dilution will be greater with larger waves breaking into the cove and carrying greater
volumes of fresh seawater through the cove and diluting and dispersing effluent.
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Overall, therefore, the dilutions measured on 12 April 2012 are likely to represent the lower
range of dilutions that may occur under the present flows. Dilutions will usually be higher at
high tides and during periods of larger swell.
7.5 Conclusions to water quality and mixing
The results on 12 April 2012 represent conditions during the period of effluent discharge on
a day of relatively low mixing and dilution conditions. The rock boundaries of the cove
constrain mixing and dispersion of effluent particularly at low tide when water volume in the
cove is relatively low and effluent accumulates in the head of the cove and can only disperse
from the cove mouth to the east of the cove.
It is most likely that concentrations would be lower within the cove and nearby waters
between discharge time, during periods of higher ocean swell and at periods of high tide
when effluent mixes through a greater depth and volume within the cove and can disperse
over the rock platforms to the north of the cove as well as the mouth of the cove to the east.
These high mixing conditions occur more often than the low mixing conditions during
sampling on 12 April 2012. Therefore water quality over an annual period would be likely to
be closer to the SEPP trigger values than those measured on 12 April 2012.
Effluent dilutions will become lower in the cove as effluent flows increase in the future.
Hence, water quality constituent concentrations in the cove will become higher as the
population connected to the Cowes STP increases.
7.6 Recommendations for water quality
It is recommended that
A mixing zone of 100 m for water quality objective be applied to the discharge from
the outlet; and
More regular water quality sampling be considered over a 12 month period to
document water quality conditions in the cove and adjacent waters over a range of
environmental and effluent discharge conditions.
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8 ECOTOXICITY TESTS
The context of ecotoxicity testing of Cowes STP effluent is Clause 27 of SEPP Waters of
Victoria, which states that:
27. Management of discharges to surface waters To protect beneficial uses, the discharge of wastes and wastewater from licensed and unlicensed premises and activities to surface waters must be managed in accordance with the waste hierarchy, with priority given to avoiding the generation of wastewater. In licensing a wastewater discharge, the Environment Protection Authority will: …
(4) not approve a wastewater discharge that, according to toxicity tests approved by the Environment Protection Authority, displays acute lethality at the point of discharge or causes chronic impacts outside any declared mixing zone, except that a waste discharge containing a non-persistent substance that degrades within any declared mixing zone may be approved.
8.1 Background to toxicity risk assessment
Eco-toxicity tests are toxicity tests that subject plants or animals (or their larvae or eggs) that
might be found in the natural environment to a range of chemical or effluent concentrations.
The tests are carefully controlled laboratory experiments that use, in this case, final effluent
direct from the treatment plant.
The test biota are placed in replicated dilutions of effluent with seawater for a set duration of
time in the laboratory. Test biota are also placed in control solutions containing just seawater
and no effluent. After the period of the test, the number of individuals in the test dilutions
that have responded differently from the control preparations are counted and the ecotoxicity
in relation to dilution is calculated.
Acute lethal toxicity tests may defined by the result of the test being measured as death or
morbidity of the test organism. Chronic toxicity tests attempt to detect long term effects of
exposure to dilute wastewater. In practice, chronic laboratory tests are relatively short in
duration and are defined by the end point being measured as a change in rate of a
metabolic, developmental or reproductive process or physical activity of the test organism
relative to the control preparations. These short chronic tests are also called sub-acute tests.
Various bioassay tests have been rigorously documented and have been accepted by
ecotoxicologists. Not all test organisms are relevant to the Victorian marine environment
(prawns and oysters, for example), and few of the range of tests using organisms found in
Victoria are routinely carried out. As a consequence a relatively small number of marine
biota (adults or life-stages) are readily available for acute and chronic tests or are relevant to
Victoria’s marine environments.
One acute and three chronic bioassays were selected for use on Cowes WRP effluent in
2010 and 2011.
Acute test:
Allorchestes compressa 96 hour survival assay. Allorchestes is a small amphipod
crustacean that is found along the Victorian coastline. It is commonly used to assess
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the acute toxicity of reclaimed water discharges from treatment plants along the
Victorian coast.
Chronic tests:
i. Hormosira banksii 72 hour germination assay: Hormosira is a common intertidal
macroalga that is found along the Victorian coastline including parts of Port Phillip
Bay. It was found to sensitive to sewage effluent during tests carried out for the
CSIRO Boags Rocks environmental study.
ii. Nitzschia closterium: 96 hour microalgal growth: This test is a very useful and
sensitive test which provides information on both growth inhibition and growth
stimulation. The tests have been widely used so that there is sufficient information for
results to be assessed for the effects of ammonia in the effluent as both a toxicant
and growth stimulant.
iii. Bivalve (Mimachlamys asperima or Mytilus galloprovincialis) 48 hour larval
abnormality test: This test using doughboy scallop larvae was found to be very
sensitive during the Boags Rocks study and provides an invertebrate sublethal link
with the invertebrate acute test (Allorchestes)
All of the bioassays recommended and used are tests that:
have acceptance by ecotoxicologists;
are relevant to Victoria;
have rigorously validated protocols and;
are applied to other discharges in Victoria.
Some effluent constituents (notably ammonia) can stimulate plant growth at some
concentrations and inhibit growth at higher concentrations. The Nitzschia growth test was
chosen because it is a marine microalga and:
(1) the test results can be checked with known responses to ammonia to determine how
much of the toxicity response of Nitzschia was due to ammonia in the effluent tested;
(2) the test results can indicate concentrations of effluent that may stimulate growth and
(3) Nitzschia is used to test effluent toxicity at other coastal treatment plants in Victoria and
the results will be useful in comparisons of effluent toxicity with other effluents.
In general terms, toxicity is tested by serially diluting effluent by 50% with control water
resulting in five test dilution preparations:
100% effluent;
50% effluent;
25% effluent;
12.5 % effluent and;
6.25% effluent.
Test organisms are placed in replicated dilutions of effluent for a set duration. The dilution at
which responses occur after the test duration are recorded relative to control waters. The
responses are
(1) the lowest concentration at which a response occurred that was statistically
significantly different from the control preparation or LOEC and
(2) the concentration at which no response occurred or NOEC.
If the NOEC is less than 100% effluent, then a statistical interpolation is used to determine
the effluent concentration at which 50 percent of the test organisms were affected. This
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concentration is known as the EC50 (effect concentration at which 50% of organisms
responded) or IC50 (inhibition concentration at which growth was 50 percent less than the
growth rate in control water). The EC50 allows a comparison of the results on a continuous
scale of effluent dilution (0 percent to 100 percent), rather than the incremental results of
NOEC and LOEC that can only be expressed in terms of the five dilution preparation, which
are in this case 100 %, 50 %, 25 %, 12.5 % and 6.3 %.
8.2 Results of toxicity tests on Cowes STP effluent
The results of toxicity tests on the Cowes STP effluent from 2010 to 2012 are shown in
Table 10. Tests in July 2012 used the two tests that were found to be most sensitive in the
2010 and 2011 series.
Table 10. Summary of effluent toxicity tests 2010, 2011, 2012 Test Statistic 2010 2011 2012
W30 W30 Outfall Outfall
Acute
Crustacean, 96 hour EC50 16.9 >100 >100
NOEC 12.5 100 100
LOEC 25 >100 >100
Toxic units 6 <1 <1
Chronic
Bivalve, 48 hour EC50 15.7 >100 48
NOEC 6.3 100 25
LOEC 12.5 >100 50
Toxic units 6 <1 2.1
Macroalga, 72 hour EC50 37.4 >100 >100
NOEC 12.5 100 100
LOEC 25 >100 >100
Toxic units 3 <1 <1
Microalga, 96 hour IC50 <6.3 75.2 74.6 >100
NOEC <6.3 50 25 50
LOEC 6.3 100 50 100
Toxic units >15 1.3 1.3 <1
Effluent toxicity tests of Cowes STP effluent in May 2010 using four tests found that the
effluent was acutely toxic to the standard test species and showed moderate chronic toxicity
to invertebrate and seaweed development and high toxicity to phytoplankton growth (Table
10). The toxicity was determined to be due to relatively high concentrations of disinfection
chemicals that were added to effluent at the treatment plant to ensure low bacteriological
concentrations in the marine environment.
The effluent disinfection system at the Cowes STP was modified in 2011 to lower the effluent
disinfection dosing rate. This action substantially reduced the toxicity of the effluent to all four
or the test species (Table 10). As a consequence, it was recommended that annual
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monitoring of potential toxicity of effluent include the most sensitive plant species chronic
test Nitzschia, and animals species chronic test Mytilus.
Tests in July 2012 showed very mild response of Nitzschia to effluent (<1 TU) and mild
response of Mytilus to effluent (2.1 TU). The mild pattern of chronic responses indicated that
acute toxicity was unlikely and the chronic response was possibly to be due to low
concentrations of ammonia in the effluent.
Calculations of effluent dilution in the cove (Section 7.4) show that minimum effluent dilutions
of 15:1 effluent occur in the cove within 20 m of the effluent discharge. This is substantially
higher than the 1:3 dilution (25 percent effluent) which resulted in no chronic response in the
most sensitive chronic bioassay in 2012.
It is expected that the effluent dilution within the cove and the intermittent effluent flow and
low exposure of biota to effluent will protect the marine ecosystem from chronic toxicity
effects outside the cove.
8.3 Implications and recommendations
Monitoring of effluent quality from the Cowes STP shows that effluent is relatively
consistent in quality.
Toxicity tests show that effluent toxicity is negligible to mild.
The effluent is not acutely toxic and therefore complies with SEPP(WoV) as suitable
for discharge to the aquatic environment with respect to acute toxicity.
It is expected that the effluent dilution provided in the cove as well as the intermittent
nature of the effluent discharge will protect the marine ecosystem from chronic
toxicity effects outside the cove.
It is recommended that
o Ammonia concentrations in the effluent be maintained at a low level
o Disinfection chemicals be dosed at the minimum amount required to maintain
primary contact recreation water quality standards and that
o The chronic toxicity of the effluent should be monitored annually using
Nitzschia and Mytilus.
It is recommended that a mixing zone for chronic toxicity be included in the discharge
licence.
9 SUMMARY AND RECOMMENDATIONS
The 2012 receiving waters monitoring program has shown that:
Intertidal marine biota in vicinity of the effluent discharges were typical of marine
ecological communities along the central Victorian ocean coastline.
o The biological community within the cove showed evidence of modified
ecological structure which is characteristic of a community affected by low to
moderately elevated levels of nutrients and ammonia.
o The affected area is characterised by
relatively high abundance of the coralline red alga Corallina officinalis
and the brown alga Colpomenia sinuosa and
the absence of the brown seaweeds Durvillaea potatorum and
Hormosira banksii
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The effluent sensitive species bull kelp (Durvillaea potatorum) and
Neptunes necklace (Hormosira banksii) were present with 70 m and
40 m of the outlet respectively.
o The influence of the wastewater discharge on the marine ecosystem is
localised but appears to be gradually increasing in intensity within the cove
and possibly is spreading to the north of the cove
o The biological community outside the cove where the outlet is located was
typical of unaffected, high wave energy communities along the coast.
Ambient water quality was strongly influenced during the discharge of effluent within
the cove where the outlet is located, with effluent dispersing along the shoreline to
the north within the cove before dispersing across the rock platforms as the tide rose
and offshore.
o Ammonia concentrations were below the SEPP trigger value for the effluent
quality and mixing conditions in 12 April 2012
o Total nitrogen concentrations on 12 April 2012 were above the SEPP 75
percentile water quality objective and it is likely that the ambient total nitrogen
concentration in ocean water is naturally relatively high
o The total phosphorus concentrations on 12 April 2012 were above the SEPP
75 percentile water quality objective for the effluent quality and mixing
conditions at all sites within the cove and to between 100 and 170 m north of
the cove.
o It is likely that water quality in the cove and adjacent waters is
Toxicity studies of the effluent indicate that the effluent is not acutely toxic and has no
to low chronic toxicity in standard laboratory tests. It is likely that the risk of toxicity to
marine biota in the vicinity of the discharge is neglible due to the consistent quality of
the effluent and intermittent low exposure of the marine biota to the dilute effluent
discharged into the marine environment.
The discharge licence for the Cowes STP should include a mixing zone extending
100 m from the point of discharge to enable the discharge to comply with the intent
and objectives of the Waters of Victoria Policy.
Annual monitoring of marine ecosystems ecotoxicity and water quality should continue as a licence condition and/or management responsibility for the next three years to (1) confirm that the discharge complies with the EPA Water of Victoria Policy and (2) comply with the Policy requirement for “a monitoring program to assess the impact of the wastewater discharge on beneficial uses”.
o The program should be reviewed after three years to formally inform
wastewater discharge management and ongoing licence compliance.
10 REFERENCES
CEE (2009) “Treated Effluent Discharge at Phillip Island. Marine Environmental
Considerations”. Report to Westernport Water. S Chidgey, CEE Consultants Pty Ltd.
August 2009
Light, BR. and Woelkerling, Wm J. (1992) “Literature and Information Review of the Benthic
Flora of Port Phillip Bay, Victoria, Australia”. Technical Report No. 6. CSIRO Port
Phillip bay Environmental Study, Melbourne.
Marine ecosystem monitoring. Ecology, water quality and ecotoxicity 40
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Keough M, Quinn GP (1991) “Causality and the Choice of Measurements for Detecting
Human Impacts in Marine Environments”. Australian Journal of Marine and
Freshwater Research 42: 539-554
State Environmental Protection Policy (Waters of Victoria) (2003)
